The A64 is closed in both directions close to the Scarborough Road junction at the eastern end of the Malton bypass.
Other emergency services are on scene with traffic being diverted through Malton in both directions.
Traffic heading eastbound is being diverted into Malton at the start of the bypass just west of the town. Traffic heading westbound is being diverted off at the Norton turn off.
Police have appealed for witnesses. On a post on social media they wrote:
"If you were driving along the A64 in this area at around 5pm this afternoon you may be able to help us establish the circumstances surrounding the collision. We would urge you to get in touch".