Two women have died and a 10-year-old girl is in hospital with life-threatening injuries after an articulated lorry collided with an Audi car on the M25.
A man has been arrested on suspicion of causing death by dangerous driving following the crash at Waltham Abbey, Essex Police said.
It happened just after 11.20pm on Monday on the anti-clockwise carriageway between junctions 26 and 27.
Two women were pronounced dead at the scene, and a man and a girl were taken to hospital.
The man was not injured.
A 32-year-old man remains in police custody.
Police are investigating the crash and the events leading up to it.
Witnesses are asked to contact Essex Police’s Serious Collision Investigation Unit on 101 or email collisionappeal@essex.pnn.police.uk.