A person was killed and another left fighting for life after a car smashed into a tree and overturned on the A12 in east London early on Monday.
Rush-hour commuters faced long delays as a three-mile queue stretched from Harold Wood, near Romford to the M25 Brook Street roundabout.
The Met said a vehicle with two occupants struck the tree at around 2am. Both were critically injured and one later died.
The dual carriageway remains closed southbound between Petersfield Avenue and Gubbins Lane.