A child is in hospital with injuries that are believed to be life-threatening after being hit by a car.
Avon & Somerset Police said just before 14:00 GMT a BMW left the road on Long Cross, in Lawrence Weston, Bristol, and hit the child.
An 18-year-old man has been arrested on suspicion of causing serious injury by dangerous driving and driving whilst unfit through drink or drugs.
Officers said they were still trying to identify a woman who was also seen in the car, as both had fled the scene.
They want anyone who saw the incident or has CCTV footage to get in touch by calling 101.
Witnesses told officers the woman had blonde hair and was wearing a black puffer coat, blue jeans and light-coloured shoes.
Long Cross was closed for several hours and multiple police, fire and ambulance crews were called to the scene.
A spokesperson from the South Western Ambulance Service NHS Foundation Trust, said: “We received a 999 call at 13:51 regarding an incident on Kings Weston Road, Bristol.
“We dispatched a Hazardous Area Response Team, two land ambulances and additional resources to the scene.”