The terrorist or group behind the horrific Boston Marathon carnage detonated two bombs made from kitchen pressure cookers packed with metallic pieces and nails - a method that has been featured in a notorious terror propaganda article.
The twin bombing at the finish line of the historic race killed at least three people - including 8-year-old Martin Richard and 29-year-old Krystle Campbell - while injuring 183 others.
A bomb designed from a pressure cooker is a preferred weapon of al Qaeda terrorists, and was listed as the 'most effective' weapon of jihad in the English-language terror magazine called Inspire.
Instructions on how to build a pressure cooker bomb were featured in the infamous Inspire article 'Make a Bomb in the Kitchen of Your Mom.'
Scroll down for video
Aftermath: Smoke billows over the finish line after the first bomb was detonated, inflicting tragedy and panic at the race
Kitchen bomb: The pressure cooker bomb is known as a 'highly effective' weapon of al Qaeda
Bomb probe: Investigators survey the site of one of the bomb blasts on Boylston Street on Tuesday - a day after two explosions struck at the Boston Marathon in Boston
A preliminary probe by Boston officials has revealed that they were made of two 1.6-gallon appliances - one containing shards of metal and ball bearings and the other packed with nails - and both stuffed into duffel bags, said a source close to the investigation.
The method used to make the bomb is reminiscent of the failed attempt to bomb Times Square by Faisal Shahzad in 2010 - and other terror strikes in India, Afghanistan, Nepal and Pakistan.
Terror guide: Instructions on how to build a pressure cooker bomb were featured in the notorious Inspire article 'Make a Bomb in the Kitchen of Your Mom'
Instructions on how to construct such a device are also readily accessible on the internet and easy to follow.
A source told the Boston Globe today that investigators located a circuit board that may have been used to detonate the devices.
Another Inspire article has insisted that a good time to 'inflict maximum human losses' is during a sporting event.
The article reads: 'There are numerous such targets such as crowded sports arenas, annual social events, large international exhibitions, crowded market-places, skyscrapers, crowded buildings.'
Shahzad was sentenced to life in prison in the Times Square attempt, which was foiled when a street vendor near Shahzad's explosives-laden SUV saw it smoking and flagged down police officers.
Similar pressure-cooker explosives have been used in Afghanistan, India, Nepal and Pakistan, according to a July 2010 joint FBI and Homeland Security intelligence report.
'Placed carefully, such devices provide little or no indication of an impending attack,' the report said.
The Pakistani Taliban, which claimed responsibility for the 2010 attempt in Times Square, has denied any role in the Boston Marathon attack.
Terror in Times Square: A pressure cooker bomb was one of the devices used in a foiled attempt to attack New York City in 2010
Pressure cooker devices were also used in the 2006 train bombings in Mumbai, India, which killed 209 people and injured hundreds more.
In Boston yesterday, the bombs had been placed in black duffel bags in a possible effort to make the dangerous explosives look like items discarded by runners or race attendees.
Weapon: The method used to make the bomb is reminiscent of the failed attempt to bomb Times Square by Faisal Shazad in 2010 - and other terror strikes in India, Pakistan and Afghanistan
They were packed with shrapnel, the person said.
The person said law enforcement officials have some of the bomb components but do not yet know what was used to set off the explosives.
A doctor treating the wounded appeared to corroborate the person's account, saying one of the victims was maimed by what looked like ball bearings or BBs. Doctors also said they removed a host of sharp objects from the victims, including nails that were sticking out of one little girl's body.
Initial tests showed no use of C-4 or other high-grade explosives, suggesting that the packages detonated in the attack were crude explosive devices, federal law enforcement officials said.
The twin blasts from the bombs took place about 12 seconds and about 100 yards apart, ripping through spectators and causing a runner at least 30 yards from one of the blasts to collapse to the ground.
Three people - including 8-year-old Martin Richard and 29-year-old Krystle Campbell - died in the twin blasts and at least 183 were injured.
Twenty-three people are listed in critical condition.
The explosions occurred near the final yards of the 26-mile and 385-yard expanse, where spectators were cheering runners as they approached the finish line.
Bomb site: The two devices were packed with metal objects and placed low to the ground, which could explain why so many victims lost feet, calves and ankles in the horrific explosions
'Crude bombs': Both of the bombs were small, likely homemade devices and initial tests showed no C-4 or other high-grade explosive material
In addition, the attack may have been specifically timed for the four-hour mark of the marathon for maximum bloodshed, as it's typically a crowded time near the finish line.
SMALL BUT DEADLY: PRESSURE COOKERS IN TERROR ATTACKS
February 2013: A bomb hidden in a pressure cooker explodes inside a restaurant in northern Afghanistan, killing five people.
October 2012: French police find bomb-making materials in an underground parking lot near Paris as part of a probe into an attack on a kosher grocery. The discovery includes bags of potassium nitrate, sulfur, headlight bulbs and a container used as a makeshift pressure cooker.
May 2012: U.S. jurors hear that explosives experts had found a pressure cooker containing smokeless gunpowder and other material in the Texas motel room of a soldier accused of planning to blow up Fort Hood military troops and other personnel.
May 2010: One of the three devices used in the May 2010 Times Square attempted bombing was a pressure cooker, according to a joint FBI and Homeland Security intelligence report issued in July 2010.
March 2010: Suspected militants attack the U.S.-based Christian aid group World Vision in northwestern Pakistan, killing six Pakistani employees. Officials say the attackers remotely detonated a pressure cooker bomb.
March 2006: A series of bombings kill 20 people in India. One bomb - at a temple in the northern city of Varanasi where five people died - was placed in a pressure cooker and detonated by a timing device.
December 2004: Ten accused Islamic militants are convicted for their roles in a plot to blow up a Christmas market in the eastern French city of Strasbourg on New Year’s Eve 2000. Authorities say the group had planned to blow up containers packed with explosives, a technique they allegedly learned in Afghan camps.
August 2002: Explosives packed in a pressure cooker shake a shopping mall in Katmandu, the capital of Nepal. Shops are damaged but there are no casualties.
Despite early reports of additional bombs, Massachusetts Gov Deval Patrick and Gene Marquez of the FBI said that only the two exploding devices near the finish line were the only ones found.
The two detonated explosives were packed with metal objects and placed low to the ground, which could explain why so many victims lost feet, calves and ankles in the horrific explosions.
Massachusetts General Hospital's chief trauma surgeon George Velmahos said today that a variety of sharp metal fragments were extracted from victims, including pellets and nails.
He told reporters: 'The [victims] are in a rather stable condition, and thank God they’re all alive.'
Dr Velmahos added: 'The experience has been overwhelming; …we’re suffering emotionally for what happened to the people of Boston and many others. At the same time, we can’t help but feel proud because the medical community at Massachusetts General responded in an amazing way.'
At a news conference this morning, police and federal agents urged anyone who may have photos or video of the finish line both before and after the bombing to come forward.
Richard DesLauriers, the chief FBI agent in Boston, vowed: 'We will go to the ends of the Earth to identify the subject or subjects who are responsible for this despicable crime, and we will do everything we can to bring them to justice.'
The blasts from the two explosive devices were so loud that doctors at MGH yesterday were treating at least one person for a shattered ear drum, in addition to the other, more severe injuries.
Dr Peter Fagenholz, another MGH trauma surgeon, said last night that the hospital had received 29 victims - and eight were critically injured.
He said that the most common serious injury was lower combined extremity injuries - affecting the bones, soft tissue and blood vessels.
'We're seeing a lot of shrapnel injuries' from small metal debris, Dr Fagenholz told reporters outside the hospital.
Federal authorities are classifying the bombings as a terrorist attack, but it's not clear whether the origin was domestic or foreign, law enforcement officials say.
Investigators said a ‘darker-skinned or black male’ with a black backpack and sweatshirt was spotted trying to get into a restricted area about five minutes before the first explosion, according a law enforcement advisory obtained by CNN.
The bombings occurred about four hours into the race and two hours after the men's winner crossed the line.
By that point, more than 17,000 of the runners had finished the race but thousands more were still running.
Boston Marathon bombing caught on video WARNING GRAPHIC CONTENT
Boston Marathon bombings: Runner's point of view
Lucky escape: A man who was hit by the blast walks away from the scene with shredded pants
BOSTON IS STRONG AND RESILIENT: OFFICIAL STATEMENT FROM MARATHON
Statement from Thomas Grilk, Executive Director of the Boston Athletic Association Tuesday, April 16, 2013
The Boston Athletic Association (B.A.A.) extends its deepest sympathies to all those who were affected by Monday's tragic events.
Those who lost their lives and were injured are in our thoughts and prayers.
It is a sad day for the City of Boston, for the running community, and for all those who were here to enjoy the 117th running of the Boston Marathon.
What was intended to be a day of joy and celebration quickly became a day in which running a marathon was of little importance.
We want to express our deepest gratitude to all of the B.A.A. medical personnel and volunteers and the City of Boston’s first responders who reacted so courageously to help save lives.
Special thanks to the loyal Boston Marathon community – over 8500 volunteers, 1000 medical personnel, the organizing committee, and hundreds of thousands along the race route – who make the experience what it is for all our runners, who are hurting today.
We would like to thank the countless people from around the world who have reached out to support us over the last 24 hours.
We are cooperating with the City of Boston, the Commonwealth of Massachusetts, and all federal law enforcement officials in the investigation and the effort to bring those responsible for this tragedy to justice, so we are limited in what information we can provide.
Boston is strong. Boston is resilient. Boston is our home. And Boston has made us enormously proud in the past 24 hours.
The Boston Marathon is a deeply held tradition – an integral part of the fabric and history of our community.
We are committed to continuing that tradition with the running of the 118th Boston Marathon in 2014.
The twin bombing at the finish line of the historic race killed at least three people - including 8-year-old Martin Richard and 29-year-old Krystle Campbell - while injuring 183 others.
A bomb designed from a pressure cooker is a preferred weapon of al Qaeda terrorists, and was listed as the 'most effective' weapon of jihad in the English-language terror magazine called Inspire.
Instructions on how to build a pressure cooker bomb were featured in the infamous Inspire article 'Make a Bomb in the Kitchen of Your Mom.'
Scroll down for video
Aftermath: Smoke billows over the finish line after the first bomb was detonated, inflicting tragedy and panic at the race
Kitchen bomb: The pressure cooker bomb is known as a 'highly effective' weapon of al Qaeda
Bomb probe: Investigators survey the site of one of the bomb blasts on Boylston Street on Tuesday - a day after two explosions struck at the Boston Marathon in Boston
A preliminary probe by Boston officials has revealed that they were made of two 1.6-gallon appliances - one containing shards of metal and ball bearings and the other packed with nails - and both stuffed into duffel bags, said a source close to the investigation.
The method used to make the bomb is reminiscent of the failed attempt to bomb Times Square by Faisal Shahzad in 2010 - and other terror strikes in India, Afghanistan, Nepal and Pakistan.
Terror guide: Instructions on how to build a pressure cooker bomb were featured in the notorious Inspire article 'Make a Bomb in the Kitchen of Your Mom'
Instructions on how to construct such a device are also readily accessible on the internet and easy to follow.
A source told the Boston Globe today that investigators located a circuit board that may have been used to detonate the devices.
Another Inspire article has insisted that a good time to 'inflict maximum human losses' is during a sporting event.
The article reads: 'There are numerous such targets such as crowded sports arenas, annual social events, large international exhibitions, crowded market-places, skyscrapers, crowded buildings.'
Shahzad was sentenced to life in prison in the Times Square attempt, which was foiled when a street vendor near Shahzad's explosives-laden SUV saw it smoking and flagged down police officers.
Similar pressure-cooker explosives have been used in Afghanistan, India, Nepal and Pakistan, according to a July 2010 joint FBI and Homeland Security intelligence report.
'Placed carefully, such devices provide little or no indication of an impending attack,' the report said.
The Pakistani Taliban, which claimed responsibility for the 2010 attempt in Times Square, has denied any role in the Boston Marathon attack.
Terror in Times Square: A pressure cooker bomb was one of the devices used in a foiled attempt to attack New York City in 2010
Pressure cooker devices were also used in the 2006 train bombings in Mumbai, India, which killed 209 people and injured hundreds more.
In Boston yesterday, the bombs had been placed in black duffel bags in a possible effort to make the dangerous explosives look like items discarded by runners or race attendees.
Weapon: The method used to make the bomb is reminiscent of the failed attempt to bomb Times Square by Faisal Shazad in 2010 - and other terror strikes in India, Pakistan and Afghanistan
They were packed with shrapnel, the person said.
The person said law enforcement officials have some of the bomb components but do not yet know what was used to set off the explosives.
A doctor treating the wounded appeared to corroborate the person's account, saying one of the victims was maimed by what looked like ball bearings or BBs. Doctors also said they removed a host of sharp objects from the victims, including nails that were sticking out of one little girl's body.
Initial tests showed no use of C-4 or other high-grade explosives, suggesting that the packages detonated in the attack were crude explosive devices, federal law enforcement officials said.
The twin blasts from the bombs took place about 12 seconds and about 100 yards apart, ripping through spectators and causing a runner at least 30 yards from one of the blasts to collapse to the ground.
Three people - including 8-year-old Martin Richard and 29-year-old Krystle Campbell - died in the twin blasts and at least 183 were injured.
Twenty-three people are listed in critical condition.
The explosions occurred near the final yards of the 26-mile and 385-yard expanse, where spectators were cheering runners as they approached the finish line.
Bomb site: The two devices were packed with metal objects and placed low to the ground, which could explain why so many victims lost feet, calves and ankles in the horrific explosions
'Crude bombs': Both of the bombs were small, likely homemade devices and initial tests showed no C-4 or other high-grade explosive material
In addition, the attack may have been specifically timed for the four-hour mark of the marathon for maximum bloodshed, as it's typically a crowded time near the finish line.
SMALL BUT DEADLY: PRESSURE COOKERS IN TERROR ATTACKS
February 2013: A bomb hidden in a pressure cooker explodes inside a restaurant in northern Afghanistan, killing five people.
October 2012: French police find bomb-making materials in an underground parking lot near Paris as part of a probe into an attack on a kosher grocery. The discovery includes bags of potassium nitrate, sulfur, headlight bulbs and a container used as a makeshift pressure cooker.
May 2012: U.S. jurors hear that explosives experts had found a pressure cooker containing smokeless gunpowder and other material in the Texas motel room of a soldier accused of planning to blow up Fort Hood military troops and other personnel.
May 2010: One of the three devices used in the May 2010 Times Square attempted bombing was a pressure cooker, according to a joint FBI and Homeland Security intelligence report issued in July 2010.
March 2010: Suspected militants attack the U.S.-based Christian aid group World Vision in northwestern Pakistan, killing six Pakistani employees. Officials say the attackers remotely detonated a pressure cooker bomb.
March 2006: A series of bombings kill 20 people in India. One bomb - at a temple in the northern city of Varanasi where five people died - was placed in a pressure cooker and detonated by a timing device.
December 2004: Ten accused Islamic militants are convicted for their roles in a plot to blow up a Christmas market in the eastern French city of Strasbourg on New Year’s Eve 2000. Authorities say the group had planned to blow up containers packed with explosives, a technique they allegedly learned in Afghan camps.
August 2002: Explosives packed in a pressure cooker shake a shopping mall in Katmandu, the capital of Nepal. Shops are damaged but there are no casualties.
Despite early reports of additional bombs, Massachusetts Gov Deval Patrick and Gene Marquez of the FBI said that only the two exploding devices near the finish line were the only ones found.
The two detonated explosives were packed with metal objects and placed low to the ground, which could explain why so many victims lost feet, calves and ankles in the horrific explosions.
Massachusetts General Hospital's chief trauma surgeon George Velmahos said today that a variety of sharp metal fragments were extracted from victims, including pellets and nails.
He told reporters: 'The [victims] are in a rather stable condition, and thank God they’re all alive.'
Dr Velmahos added: 'The experience has been overwhelming; …we’re suffering emotionally for what happened to the people of Boston and many others. At the same time, we can’t help but feel proud because the medical community at Massachusetts General responded in an amazing way.'
At a news conference this morning, police and federal agents urged anyone who may have photos or video of the finish line both before and after the bombing to come forward.
Richard DesLauriers, the chief FBI agent in Boston, vowed: 'We will go to the ends of the Earth to identify the subject or subjects who are responsible for this despicable crime, and we will do everything we can to bring them to justice.'
The blasts from the two explosive devices were so loud that doctors at MGH yesterday were treating at least one person for a shattered ear drum, in addition to the other, more severe injuries.
Dr Peter Fagenholz, another MGH trauma surgeon, said last night that the hospital had received 29 victims - and eight were critically injured.
He said that the most common serious injury was lower combined extremity injuries - affecting the bones, soft tissue and blood vessels.
'We're seeing a lot of shrapnel injuries' from small metal debris, Dr Fagenholz told reporters outside the hospital.
Federal authorities are classifying the bombings as a terrorist attack, but it's not clear whether the origin was domestic or foreign, law enforcement officials say.
Investigators said a ‘darker-skinned or black male’ with a black backpack and sweatshirt was spotted trying to get into a restricted area about five minutes before the first explosion, according a law enforcement advisory obtained by CNN.
The bombings occurred about four hours into the race and two hours after the men's winner crossed the line.
By that point, more than 17,000 of the runners had finished the race but thousands more were still running.
Boston Marathon bombing caught on video WARNING GRAPHIC CONTENT
Boston Marathon bombings: Runner's point of view
Lucky escape: A man who was hit by the blast walks away from the scene with shredded pants
BOSTON IS STRONG AND RESILIENT: OFFICIAL STATEMENT FROM MARATHON
Statement from Thomas Grilk, Executive Director of the Boston Athletic Association Tuesday, April 16, 2013
The Boston Athletic Association (B.A.A.) extends its deepest sympathies to all those who were affected by Monday's tragic events.
Those who lost their lives and were injured are in our thoughts and prayers.
It is a sad day for the City of Boston, for the running community, and for all those who were here to enjoy the 117th running of the Boston Marathon.
What was intended to be a day of joy and celebration quickly became a day in which running a marathon was of little importance.
We want to express our deepest gratitude to all of the B.A.A. medical personnel and volunteers and the City of Boston’s first responders who reacted so courageously to help save lives.
Special thanks to the loyal Boston Marathon community – over 8500 volunteers, 1000 medical personnel, the organizing committee, and hundreds of thousands along the race route – who make the experience what it is for all our runners, who are hurting today.
We would like to thank the countless people from around the world who have reached out to support us over the last 24 hours.
We are cooperating with the City of Boston, the Commonwealth of Massachusetts, and all federal law enforcement officials in the investigation and the effort to bring those responsible for this tragedy to justice, so we are limited in what information we can provide.
Boston is strong. Boston is resilient. Boston is our home. And Boston has made us enormously proud in the past 24 hours.
The Boston Marathon is a deeply held tradition – an integral part of the fabric and history of our community.
We are committed to continuing that tradition with the running of the 118th Boston Marathon in 2014.