Police believe a man shot several times at Erskine Park in Sydney's west could have been a victim of mistaken identity.

Selahattin Koyuncuoglu, 25, was sitting in his van outside a relative's house on Fantail Crescent when he was shot several times.

He was taken inside the house where he was treated by paramedics before being taken to Westmead Hospital.

The victim remains in hospital in a critical condition.

A police spokesman told the ABC detectives were investigating whether Mr Koyuncuoglu was a victim of mistaken identity because he did not have any known links to gangs or organised crime.

But it is understood Mr Koyuncuoglu's relative, who is believed to be a cousin, has links to the Comancheros outlaw motorcycle gang.

Neighbours said the victim was shot by a person who pulled up in nearby Cobar Place in a large four-wheel drive.

The shooting was captured on CCTV from Mr Koyuncuoglu's relative's home, as well as two neighbouring properties.

Detectives are examining the footage to try to find those responsible.

Police set up a crime scene in the quiet suburban neighbourhood overnight while officers from the dog squad searched the street.

Investigators are urging anyone with information to contact them.