At least one person has been seriously injured in a crash on the M1 southbound involving two lorries and a car.
The smash took place at around 2.40pm this afternoon, between Junction 7 at St Albans and Junction 6A for the M25.
The slip road at Junction 6A has been closed, and there are traffic delays on the M1 and the M25 as a result.
A red Saab 9-3 saloon car and a white Mercedes lorry have been recovered from the scene, but there is damage to the road and diesel is spilling out onto the carriageway.
The Highways Agency are currently attempting to clear the carriageway.
Herts Police press & PR officer Dan Phillips said: “Lane 1 (the slow lane) southbound is closed on the M1 at present. There is a backlog of traffic stretching back at least as far as Junction 9.”