Police investigate possible organised crime links after 11-year-old shot in Sydney home

Police are investigating whether men present at the time an 11-year-old boy was shot in the head at a north-west Sydney home had links to organised crime, the ABC understands.

The child was treated for wounds to the face and neck and remains in a critical condition in hospital, following the incident at a Norwest home about 5pm on Monday.

An 18-year-old man has been charged with concealing a serious indictable offence, with two other men, both aged 18, released from custody after being questioned by police.

A 43-year-old woman was also present at the time of the shooting, with another person not yet located.

It is understood investigators are looking into whether the men inside the unit have links to organised crime.

Police on Monday night had said there was no evidence to suggest the incident was related to underworld tensions.

"We have nothing to suggest that it is organised crime-related, but we will conduct a very thorough investigation into this," NSW Police Superintendent Naomi Moore said.

"For those that are obviously fearful on the streets out here at the moment, we are content that we are doing a very thorough investigation here."

Superintendent Moore said the firearm had not yet been recovered.

A resident at the unit block said police could be seen searching a nearby park and creek after the shooting.

"They had cordoned off the whole park at that time and they were searching … until late in the night, I believe," he said.