A teenager has been charged after an 11-year-old boy was allegedly shot “in the face and neck” inside a luxury apartment in Sydney’s north-west.

The child was fighting for his life in hospital on Monday night and police reportedly said it would be a miracle if he survived.

His “distressed” mother spent the evening at her son’s bedside as he underwent lifesaving treatment.

Emergency services discovered the 11-year-old victim suffering a gunshot wound at a unit in Norwest, Sydney’s Hills District, about 5pm on Monday.

Police outside the upmarket property in Norwest. Photo: 9NEWS

The latest tragedy followed a weekend of violent incidents in NSW.

The boy was shot from inside the home, police said. There was “nothing to suggest” the shooting was organised crime related.

There were five other people present at the apartment complex when authorities arrived — four 18-year-old males and a woman, 44.

Superintendent Naomi Moore on Monday said the group — some relatives, some friends — were “allowed access” into the home.

Three of the men, all aged 18, were arrested.

Two were taken to The Hills Police Station and later released pending further inquiries.

The third man was taken to Riverstone Police Station, where he was charged with conceal serious indictable offence.

He was refused bail and will appear before Blacktown Local Court on Tuesday.

Detectives had no reason to suspect the shooting related to organised crime, she said, but would not speculate what occurred in the house.

Moore said the boy’s mother accompanied him in hospital.

“She is as distressed, as any parent would be, about what she is dealing with at the moment,” she told reporters.

“It is an (absolutely) tragic situation and as we’ve seen some tragedy across Sydney in the last couple of days, this is not far from the worst that I have seen.”

Moore said police were yet to locate a firearm, but no firearms were registered to the Fairway Drive address.

That fact will form a line of inquiry, she confirmed.

Police established a crime scene at the address and an investigation is continuing.

Anyone with information has been urged to contact Crime Stoppers.

-with AAP