The M25 is closed ant-clockwise between Junction 31 for Purfleet/Lakeside and Junction 30 for Aveley following a multiple vehicle collision.
There are long delays on the approach to the Dartford crossing as traffic held to implement the closure.
All emergency services are working at the scene with Highways England traffic officers, in a response being led by Essex police.
A diversion route using local routes has been implemented at J31.
A spokesman for Essex Police said :
A section of the #M25 is shut following a serious collision, which took place at about 8.20pm on Sunday 10 May.
A grey Jaguar XF was in collision with a lorry on the motorway heading into Essex close to junction 30, near #Lakeside.
The Jaguar driver, a man aged in his 50s, was taken to hospital with serious injuries.
The lorry driver, a man aged in his 40s, was not hurt.
The road is currently closed while we continue enquiries at the scene.
Witnesses and anyone with dash cam footage are asked to contact the Serious Collision Investigation Unit on 101 or email CollisionAppeal@essex.pnn.police.uk