Two people died when the car they were travelling in left a road and crashed into a field.
The grey BMW veered off the A688 while travelling north between the Coxhoe and Bowburn roundabouts at about 01:30 BST on Sunday.
A man and woman from the car were pronounced dead at the scene, a spokesman for Durham Police said.
"Their families have been informed and are being supported by specially trained officers," he added.
Officers are appealing for witnesses.