A lorry and two cars have crashed into each other on the M25 - resulting in long delays. 

All traffic has been stopped since around 11.50am following the crash on the anticlockwise carriageway from junction 17 to junction 16 for the M40. 

The traffic is being held near the Chalfont viaduct while the emergency services are on the scene of the crash, which happened in lane one. 

Eyewitnesses reported seeing one vehicle having its roof cut off by firefighters and an urban search and rescue team is assisting. 

Police are urging anyone with dashcam footage to get in touch - call 101 quoting URN 500 of 25/3/2019.