A driver who stopped and got out of his car on the A1 in North Yorkshire was killed when he was hit by a lorry.
The incident happened on the southbound carriageway near junction 48, between Allerton Park and Wetherby.
Police have appealed for any witnesses who saw the man stop and get out of his silver car to contact them.
The lorry driver was arrested at the scene, and no-one else was injured in the collision.
Diversions were expected to remain in place for hours as police shut the A1 southbound to allow for investigations.
A North Yorkshire Police spokeswoman said the incident involved a silver car which stopped on the carriageway and an HGV which was in collision with the car.
She added: “The male driver and sole occupant of the car stood on the carriageway at the time of the collision and sadly he died as a result of the crash.
“Officers need to establish why the man had stopped and got out of his car and are appealing to anyone who saw the stationary silver car and a man on the southbound carriageway.”