A woman died and a man has been arrested as a car collided with a digger.
The 29-year-old victim was believed to have been a passenger in a BMW 3 Series car which hit the digger in the A138 in Boreham, Essex, just after 03:10 BST.
She died at the scene and a 23-year-old man, believed to be the car's driver, was arrested on suspicion of causing death by dangerous driving.
Both he and a woman - a second passenger - suffered serious injuries.
The arrested man was also detained on suspicion of causing serious injury by dangerous driving and driving while unfit.
The road between the Pump Lane junction of the A138 and Boreham Interchange on the A12 near Chelmsford was closed while forensic collision investigation work was carried out and was expected to remain so into Saturday evening.
Essex Police has called for anyone with any information to come forward.