Horror as two teenage boys are stabbed and beaten in the head with a hammer during a terrifying home invasion as robbers stormed the Sydney house with an axe, hammer and gun

Two teenage boys have been viciously assaulted during a violent home invasion in the middle of the night, with one boy stabbed and another bashed with a hammer.

Emergency services were called to a home on Purser Avenue, Castle Hill, north-west Sydney, at 1am on New Year's Eve. 

Officers were told seven men armed with an axe, knife, hammer and firearm entered the home and threatened those inside.

Emergency services were called to a home on Purser Avenue, Castle Hill, north-west Sydney, at 1am on New Year's Eve (street view pictured)

They demanded belongings from those inside before stabbing an 18-year-old in the stomach several times.

Another person, 17, was in the backyard when the group of men broke in and was brutally hit in the head with a hammer.

The offenders took six mobile phones before smashing up the house and driving away.

The injured teens were taken to Westmead Hospital. 

Police are looking to speak with seven men who may be able to help with their inquiries. 

Police said seven men armed with an axe, knife, hammer and firearm entered the home and threatened those inside