An air ambulance has been called after a four-car crash on the anti-clockwise M25.

Hertfordshire Constabulary was called by the East of England Ambulance Service at 11.20am after reports of a four-car collision between junction 16 (Uxbridge) and junction 17 (Maple Cross).

One of the cars is believed to have overturned and the road is currently closed while recovery work begins.