A boy who was shot in a unit in Sydney’s north-west has died after three days fighting for life in hospital.

The 11-year-old was rushed to hospital in a critical condition after being shot in the chin and neck on Monday inside a Norwest unit.

A police cordon at the scene of an alleged shooting in Norwest on Monday night. Wolter Peeters/SMH

Police said they were told about 8pm on Thursday that he had died and shared the sad news about an hour and a half later.

Speaking to media on Tuesday afternoon, Superintendent Naomi Moore said police were still trying to piece together how the gun was fired – including whether the young boy was playing with the weapon when it discharged.

At least five other people who were home at the time were not injured, though Moore said some had left before emergency services arrived.

Moore said while some people who were present had ties to organised crime, it did not mean that the shooting was connected to any “current conflicts”.

Police have not located the gun, which fired a single shot.

They said the people who were inside the unit at the time of the shooting were not cooperating with the investigation.

Superintendent Naomi Moore admitted police were still trying to ascertain how the shooting occurred. 9News

Everyone there was described as either a friend or relative of the victim.

An 18-year-old man, Isaac Bechara, has since been charged with concealing a serious indictable offence, allegedly holding back information while remaining behind bars.

Two other 18-year-old men who were arrested were released pending further inquiries.