About 10.30pm on Friday, police were patrolling Showground Road in Gosford when they attempted to stop a car, believing it to be stolen.

Despite using lights and loud sirens to signal the vehicle, the driver failed to stop and the police initiated a pursuit.

After chasing the car for a minute, it collided with another vehicle.

Five teenagers were found to be in the car and were trapped for a short time before being taken to hospital in a critical condition.

The vehicle involved in the chase is believed to be a pizza delivery car stolen in a car-jacking incident at The Entrance on January 18.

Weapons, including an imitation pistol and a knife, were allegedly found in the car, which police say will soon undergo forensic investigation.

One 17-year-old male from the vehicle has already been arrested in relation to outstanding warrants. He now remains under guard at Gosford Hospital.

Four other 17-year-olds, one female and three males, remain in serious but stable conditions at Royal North Shore Hospital, John Hunter Hospital and Liverpool Hospital.

The other car was being driven by a 43-year-old woman, who is now in a stable condition at Gosford Hospital.

Lake Macquarie Local Area Command, assisted by the Crash Investigation Unit, is investigating the incident.