Four people have been seriously injured after a car that failed to stop for police entered the motorway in the wrong direction and crashed head-on into another vehicle.
The “very serious collision” brought traffic on the M1 to a halt in West Yorkshire on Monday night.
Police say a black Skoda Fabia was driving south in the northbound carriageway and hit a blue BMW 320 which was travelling north.
A spokesperson for the West Yorkshire force said: “The Skoda had earlier failed to stop for police and went on to enter the northbound M1 in the opposite direction at Junction 40.”
The crash happened between junctions 39 and 40, near Wakefield, at around 9.10pm.
Police said the three occupants of the Skoda have all suffered serious or life-threatening injuries as a result of the collision.
The driver of the BMW also suffered serious injuries.
A referral has been made to the Independent Office for Police Conduct (IOPC), West Yorkshire Police said.
Anyone who may have witnessed the collision or the circumstance leading up to it, or who may have dashcam footage, is asked to contact West Yorkshire Police on 101, or online via www.westyorkshire.police.uk/101livechat, quoting reference 13220207510