Part of the M25 is expected to remain closed for several hours after a serious crash.
The accident involving two lorries happened on the anticlockwise side between junction 5 for the M26 and 4 for Orpington at around 6.15am.
Emergency services have closed the carriageway and traffic is unable to pass the scene.
A police spokesman said: “The M25 is currently closed between Junctions 5 and 4 anti-clockwise following a serious collision.
“Kent Police was notified of the incident involving two heavy goods vehicles at 6.17am on Friday 22 September 2017 and officers are currently at the scene.
“The hard shoulder and lane one are expected to be closed for several hours while initial enquiries are carried out.
“It is hoped that lanes two and three can be reopened earlier to help ease traffic congestion.”
Highways England says traffic officers are working with emergency services to release traffic trapped before the crash scene.
Congestion is also building up on the clockwise carriageway as traffic approaches the scene between junctions 3 and 5.
A spokesman added: “Road users are advised to allow extra time to complete their journeys or to seek an alternative route if possible.”