A 23-year-old man is being treated for head injuries after a collision between a car and a scooter just after midnight on Wednesday.
One man has been arrested on suspicion of dangerous driving after he stopped his VW Golf following the collision.
The collision happened on the A406 northbound between Ilford Hill and Gants Hill.
The injured man, who had been driving a scooter, was taken as “a priority” to the Royal London Hospital with serious head injuries.
He was accompanied by a doctor from the London’s Air Ambulance.
London Ambulance Service (LAS) sent two ambulance crews and an air ambulance to the scene.
The A406 is currently closed between Ilford Hill and Gants Hill.
Police enquiries are still ongoing.
Any witnesses who haven’t already spoken to police should call 101.
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