Two quad bikers are fighting for life in hospital after a major accident on the North Circular in Walthamstow.
The men, aged in their 30s, were among a group of bikers involved in a pile-up on the A406 close to Fulbourne Road just after 3pm.
Scotland Yard said police were called to the accident after reports of a collision between "a number of vehicles including several quad bikes".
London's Air Ambulance and a crew from the London Ambulance Service arrived at the scene and soon after took the injured men to an east London hospital.
A police spokesman described their condition on Sunday evening as "critical".
Drivers were left facing lengthy delays after police closed the road between Crooked Billet and Waterworks Corner while they investigated.
Motorists were advised to avoid the area.
Walthamstow MPS tweeted: "A406 North Circular is being closed at Walthamstow both directions, whilst we deal with serious RTC.
"Please avoid the area UFN. Insp Adams."
Detectives investigating the crash appealed for witnesses to speak to them. No arrests have been made.
Anyone with information should contact police on 101 quoting reference number CAD5810-8NOV15.
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