The A1M Northbound has been closed overnight after a crash between Wetherby and Boroughbridge.
North Yorkshire Police closed the road between junction 46 and junction 48 at around 1pm.
Sargent Paul Cording of North Yorkshire Road Policing groups tweeted to confirm that the police's forensic collision team had been at the scene of the crash overnight.
It is expected that the road will reopen this morning.
Highways England tweeted to urge motorists to allow extra time for their journeys.
It said: "No delays approaching the closure at J46, but allow extra time to travel along the diversion route."