Police are appealing for information after a crash on the A11 at Snetterton.
The incident happened at 6.45pm on Tuesday on the southbound carriageway. A Mitsubishi Charisma left the road and overturned.
One person in the car suffered serious head injuries.
Anyone who may have witnesses the collision, or the manner of driving of the car prior to the incident, should contact PC Dave Reed at Wymondham Roads Policing on 101.