Specialist crash investigators are trying to establish the cause of a serious accident on State Highway 1 south of Kawakawa which saw six people taken to hospital.
The head-on smash occurred just before 7pm on Saturday near the intersection with Waiomio Rd.
Senior Sergeant Peter Robinson, of Kerikeri police, said it appeared a northbound Toyota Hiace van had clipped the side of a Volkswagen Golf heading in the opposite direction, then collided head-on with a second southbound vehicle, a Ford Territory.
The van's two occupants and four of the six people in the Ford were taken to Bay of Islands and Whangarei hospitals by St John Ambulance.
There was no indication that alcohol or drugs were involved, he said. Fatigue and speed were being examined as possible contributing factors.