A 60-year-old man has died and three others were injured in a three-car pile-up on the M25 in north London.
A 62-year-old woman driving a Range Rover Evoque collided with a Ford Focus and a Vauxhall Corsa on junction 24 clockwise, at Enfield,about 9.45pm on Saturday, police said.
She and two others were injured.
Medics battled for two hours to save the driver of the Corsa, but despite their efforts he was pronounced dead at the scene at 11.43pm.
His 55-year-old female passenger was rushed to an east London hospital where she remains in a stable condition. Her injuries are not thought to be life-threatening.
The Range Rover driver was taken to a hospital in Hertfordshire with minor injuries and subsequently arrested on suspicion of causing death by dangerous driving.
She remains in custody at an east London police station.
The deceased man's next of kin have been informed and a post-mortem will be held.
Detectives from the Met’s Roads and Transport Policing Command are investigating and would like to speak with anyone who saw the collision.
Anyone with information is asked to contact the Serious Collision Investigation Unit’s witness appeal line at Chadwell Heath on 020 8597 4874.