Police are investigating after a patrol car and another vehicle collided on State Highway 1 at Clarence, south of Blenheim.
Police said the crash happened about 7.30pm near Dead Man Stream.
Initial indications were that the police vehicle was at fault, and a serious crash investigation would be undertaken.
Police were not immediately able to comment as to whether an independent investigation would go ahead as well.
Marlborough Area Commander Inspector Simon Feltham said none of the occupants of the vehicles suffered serious injuries; however the female passenger in the car was taken for a medical check up.
Police said the crash didn't occur while the police officer was pursuing the other vehicle or undertaking any police activity related to the other vehicle.
An independent inquiry would likely begin after the serious crash investigation had concluded.