Police say part of State Highway 2, near Maramarua in the Waikato, was closed on Tuesday evening after a crash that claimed three lives.
The accident, involving a car and a ute, happened shortly after 8pm.
Senior Sergeant Matt Sillars says those who died were all travelling in the car.
He says the driver of the ute has been taken to hospital by helicopter.
Traffic diversions were put in place.