Drivers have been warned of high levels of traffic across West Herts after a serious road traffic collision on the M25 this morning.
Police said at least two vehicles were involved in the crash on the clockwise carriageway at junction 20 for Kings Langley at 11.55am.
M25 clockwise remains shut J19-20 (A41) after the lunchtime crash; 1 hour delays from Rickmansworth.
Anti-clockwise is open but with 1 hour delays from J22 due to broken down bus in the jams.
Drivers are being diverted off the M25 and motorists have been advised to avoid the area if possible.
More to follow.