A witness to a crash involving a prison truck has described watching the horror unfold in his rear view mirror.
A prison truck with at least five prisoners inside has collided with another vehicle on State Highway 1 south of Kawakawa and one person in the other vehicle has died.
The man said he was driving directly in front of the truck when it collided with the car.
"I was watching in my mirror and saw it all happen behind me," he said.
"It looked like the car was overtaking, and hit the truck head-on."
Police, Fire and Emergency and St John staff are at the scene.
A St John spokeswoman said four ambulances and one rescue helicopter were in attendance.
A Fire and Emergency New Zealand spokeswoman said they were called to the emergency at 2.45pm and two crews from Kawakawa were in attendance.
The highway is believed to be blocked while the victims are treated and the accident scene cleared. Diversions are in place through Ruapekapeka Rd, although police said it was not suitable for heavy vehicles.
Southbound traffic is being diverted at the intersection of SH1 and SH11 at Kawakawa.
Traffic is backing up on both sides of the accident scene.
Significant delays are expected on the roading network throughout the day as the Toitū te Tiriti hīkoi protest makes its way through Auckland. Video / NZ Herald