The M5 in Somerset is closed in both directions after a 17-year-old girl died in a collision.
Avon and Somerset Police said the incident, involving a pedestrian and a car, had happened between junctions 24 for Bridgwater and 25 for Taunton at around 23:00 GMT on Monday.
The force said the girl had died at the scene and her next of kin had been informed. No one else was injured in the collision.
National Highways said the road was expected to remain closed throughout Tuesday morning, while enquiries ware carried out.
Police said a mandatory referral had been made to the Independent Office for Police Conduct due to recent prior police contact.
Anyone who witnessed the collision or may have dashcam footage which could help the investigation, is urged to contact police.