A teenage girl was in a critical condition and a teenage boy seriously injured after a road accident on Merseyside on Sunday.
The car they were driving - believed to have been stolen - was being followed by police at the time.
The accident happened just before 0500 BST at the junction of Western Avenue and Tarbuck Road, Speke, Liverpool.
A marked Vauxhall Vectra police car was following the blue Mini when it collided with two parked cars.
A 16-year-old boy, who was trapped in the Mini, had to be cut free by firefighters using cutting equipment.
Inquiry launched
He was taken to Whiston Hospital with chest and leg injuries, but is believed to have been discharged.
A 16-year-old girl was also taken to hospital with serious head injuries. Her condition is described as critical.
Officers are appealing for witnesses to the incident.
A police complaints authority investigation is under way.