A teenager is in a critical condition after a rolling a van while on a wild joy ride in Sydney's south west.

Emergency services were called just after 7.30pm on Saturday following reports a stolen HiAce van had veered off the road and flipped into the backyard of two houses on Elizabeth Drive, near Anastasio Road in Liverpool.

The 15-year-old boy was among four people travelling in the vehicle and suffered critical injuries from the impact of the crash.

It's been reported the teen was treated at the scene by NSW Ambulance Paramedics before being taken to Liverpool Hospital, where he remains under police guard.

According to New South Wales Police, the other occupants of the van, including the diver, fled the scene on foot before police arrived.

Police caught up with them a short time later and they were arrested and taken to Liverpool Police Station for questioning.

No charges have been laid.

The two houses sustained minor damage but no injuries to occupants were reported.

As inquiries into the crash continue, Sydney police are urging anyone who may have information or dashcam footage to contact Liverpool Police on 02 9765 9499 or Crime Stoppers on 1800 333 000.

- With AAP