A man has been airlifted to Queens Medical Centre in Nottingham after he was hit by a car on Little Gate Lane in Potterhanworth.
It happened at around 2.20pm when a blue Nissan Primera hit a pedestrian who was previously driving a red Citroen C2 but got out of the vehicle and was by the roadside.
It was the driver of the Citroen who was taken to hospital by Air Ambulance.
The road has been closed ever since the incident and police expect it to reopen at around 6.45pm.
Police are appealing for anyone who was driving along Little Gate Lane and saw a red Citroen C2 or a blue Nissan Primera being driven along the road, or witnessed the collision to call 101 quoting incident 174 of December 29.