A 19-year-old woman and a 21-year-old man died at the scene of the crash on the A39 near Farrington Gurney in Somerset.
They were passengers in a VW Polo which was travelling towards Bristol from Wells when the incident happened at about 8pm on Friday.
The vehicle left the road on a bend near to the junction of the A39 with the A37 at Rush Hill, police said.
Another passenger was taken to Southmead Hospital with serious injuries. The driver of the vehicle received minor injuries.
Investigators closed the road following the crash to examine the scene.Avon and Somerset Police are appealing for anyone with information to come forward.