A powerful explosion has damaged a building in the centre of the Czech capital, Prague, injuring up to 40 people.
Authorities say they believe some people are buried in the rubble.
Police spokesman Tomas Hulan says it is not certain what caused the blast in Divadelni Street, but it was likely a natural gas explosion
The street was covered with rubble and has been sealed off by police who have also evacuated people from nearby buildings and closed a wide area around the explosion site.
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Injured: A powerful explosion has damaged a building in the centre of the Czech capital Prague with people feared buried in the rubble
Cause: Police said it is not immediately clear what caused the blast in Divadelni Street this morning, but it was probably a gas explosion
Investigation: The street is covered with rubble and has been sealed off by police
Zdenek Schwarz, head of the rescue service in Prague, says up to 40 people have been injured.
Windows in buildings located hundreds of metres from the blast were shattered, including some in the nearby National Theatre.
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The explosion was heard as far as Prague Castle about a mile (1.6 km) across the Vltava river.
A police spokesman said that there had been about 15 people in the building, which included an office of the International Air Transport Association (IATA) and an art gallery.
Firefighters spokeswoman Pavlina Adamcova said rescuers were still searching the rubble, using sniffer dogs.
Rescue service spokeswoman Jirina Ernestova said there were foreigners among the injured but had no further details immediately.
Some of the injured were taken to Prague's hospitals for treatment while others, many of whom were hit by flying glass, were treated by rescuers at the scene.
Explosion injures over 40 people as it rips through Prague...
Hurt: An injured man removes his shirt before receiving medical treatment
Injured women are helped away from the scene of the blast in the Czech capital, Prague
Damage: Windows in buildings located hundreds of metres from the blast were shattered, including some in the nearby National Theatre
Tourists at the famed Charles Bridge also felt the blast.
'There was glass everywhere and people shouting and crying,' Vaclav Rokyta, a Czech student said near the scene.
'I was in the bathroom, no windows, the door was closed. Honestly, if I had been in my bed I would have been covered in glass,' said Z.B. Haislip, a student from Raleigh, North Carolina, who was in a nearby building.
The Faculty of Social Sciences of Prague's Charles University and the Film and TV School of the Academy of Sciences of Performing Arts are located next to the damaged building.
Prime Minister Petr Necas said in a statement he was 'deeply hit by the tragedy of the gas explosion.
The road closures caused major traffic disruption and confused thousands of tourists. Some new arrivals to the city had to stand on street corners, unable to reach their hotels, their baggage loaded onto trolleys. Hotel staff urged them to be patient.
Evacuate: Injured people leave the scene of the explosion
Statement: Prime Minister Petr Necas said in a statement he was 'deeply hit by the tragedy of the gas explosion'
Explosion: Injured people sit on a sidewalk after a explosion downtown Prague this morning