An unmarked police car responding to an emergency was in collision with a pedestrian in South Gloucestershire on Sunday (November 24).
The incident happened on the roundabout where the A4174 joins Badminton Road, in Emersons Green, at around 6.30pm.
The police car was using blue lights and a siren at the time of the incident.
Avon and Somerset Police said in a statement: “Officers provided first aid to the pedestrian, a 19-year-old woman, alongside paramedics. She was taken to hospital with injuries which are potentially life-changing. Her next of kin are aware and we’ll be providing them with support.
“The officers in the vehicle were not injured in the collision and will be offered welfare support.
“As is standard practice following an incident in which there’s been a serious injury following police contact, we’ve made a mandatory referral to the Independent Office for Police Conduct.”