People are reported to be injured following a "serious collision" on the M25 in Surrey.
Six ambulances and four fire engines are at the scene of the accident between junctions 10 and 11, in which two people are believed to have suffered "serious injuries".
Surrey Police said the clockwise carriageway is expected to remain closed "for some time".
More top news
A man had a "miracle escape" when his £200,000 Ferrari careered off a motorway and into a field - just an hour after he bought it.
Hundreds of towers across England were discovered to have fire safety flaws including broken fire doors and holes, new figures show.
The Post Office's abandoned underground railway opens its doors on Friday some 14 years after the last letter was transported through it.