A 21-year-old man has died after being in collision with a police car, according to the Independent Police Complaints Commission (IPCC).
The incident happened on the westbound carriageway of the A31 Hogs Back near Puttenham, Surrey, at 3.35am on Saturday.
A Surrey Police spokesman said: "The incident has been referred to the Independent Police Complaints Commission."
An IPCC spokesman said: "A fatal accident occurred on the A31.
"A 21-year-old male pedestrian has died. He was in collision with a Surrey Police car.
"Our investigators were deployed to the scene and an IPCC investigation has begun."
The westbound carriageway has been closed while the scene is examined to establish how the incident happened.