A man who was shot in stomach and chest after answering a knock at his front door in Sydney's west is believed to be the victim of a targeted attack.

Officers were called to Ismay Avenue, Homebush, about 11pm on Sunday following reports of a shooting.

On arrival, they found a man aged in his late 20s with gunshot wounds to his stomach and chest.

He was taken to Royal Prince Alfred Hospital where he underwent surgery and remains in a serious condition.

Police said the man, a father of two girls, was shot inside his home after answering a knock at the front door.

A crime scene has been established at the home which is being examined by specialist forensic officers, police say.

They are confident the shooting was a targeted incident.

The offender is believed to have fled the area in a white vehicle.

Neighbours said the victim and his partner kept to themselves but would say hello in the street.

A man who has lived across the road for 25 years said the street had been free of trouble, with the victim and his family moving in about two years ago.

"We just simply heard some banging and we thought someone might just be doing some work," he said.

Another neighbour said the she looked outside after the shots rang out.

"I heard chop, chop, chop," the woman told AAP.

"After it happened, I went to look outside. I only saw the car and some people running."