At around 6.55pm today (3 December 2011) a pedestrian was hit by several cars on the eastbound carriageway near to the Little Chef.
Officers are still trying to establish the identity of the man, who was wearing dark clothing and jeans.
The eastbound carriageway is completely closed between Headley Bar and Bilborough. It is expected to remain closed for some time to allow police to complete their enquiries into the collision.
The westbound carriageway is also completely closed between Bilborough and Tadcaster.
Police are appealing to anyone who witnessed the collision to get in touch.
Traffic Sergeant Andy Quigley, of North Yorkshire Police, said:
It is vital that anyone who witnessed the collision or saw the pedestrian prior to the incident, gets in touch with the police as soon as possible.
At this stage the victim’s identity is unknown and if you know who he might be it is important that you get in contact with any information that can help the investigation.
Anyone who can help the police with their enquiries is urged to contact North Yorkshire Police on 0845 60 60 24 7, quoting reference number NYP-03122011-0446.