A man has died following a multi-vehicle collision in east London.
Police said the crash, involving five cars, happened at about 11.10pm on Wednesday during tailbacks on the A12 eastbound in Leytonstone following an earlier collision.
A 73-year-old man was pronounced dead at the scene.
The Metropolitan Police said a BMW collided with four vehicles before hitting the central reservation.
The drivers of two of the cars - a Porsche and a Range Rover - left before police arrived, while a Ford Mondeo and Peugeot 206 remained at the scene.
The driver of the Ford moved his car to the side of the road, and was in the process of changing a wheel when he became unwell. Despite efforts from emergency services he died.
The occupants of the BMW, a white X6 Coupe with the registration OV6GYJ, abandoned the vehicle and made off, said police.
Detective Sergeant Jeff Edwards, of the Met's Serious Collision Investigation Unit, said: "This was a very serious collision involving a number of vehicles, which has sadly resulted in a man losing his life.
"Whilst we continue to speak to witnesses and will be reviewing CCTV from the area it is important we trace the occupants of the BMW who fled the scene.
"The drivers of the other vehicles involved have all been traced and are assisting us with our inquiries. I would encourage the driver of the BMW to come forward as soon as possible."
The dead man's next of kin have been informed and a post-mortem examination will be held in due course.
Witnesses or anyone with information or footage is asked to contact the Serious Collision Investigation Unit at Chadwell Heath on 020 8597 4874.