Police say a fatal crash that left four people dead in Kaingaroa Forest in the Bay of Plenty this morning involved a logging truck and a van.

Photo: Supplied / NZ police

Emergency services were called to the crash shortly before 7am.

Police say it was on a private forestry road, and four people travelling in the van died at the scene.

The truck driver was shaken but uninjured.

Fire and Emergency said one person was trapped.

St John said one person in a critical condition had been taken to Waikato Hospital by helicopter.

Three ambulances attended the scene.

Bay of Plenty Road Policing Manager Inspector Brent Crowe said the logging truck was "fully laden".

He said the road was an operational road which users needed a permit to drive on.

"There are large logging trucks that use this frequently so it's a road in very good order but you certainly have to know what you're doing to drive on this road.

"At the time of the crash it was reasonably dark, sunrise hadn't occured, and the roading conditions from what we saw appeared to be good there appeared."

He said there was a karakia held at the site this morning in front of police, transport operators, and logging truck drivers who had been in the area.

The Serious Crash Unit remain at the scene.

The area has been closed to traffic while police investigate.

Timberlands, which operates in the forest, said it is not yet in a position to comment, however it has confirmed it is working with the police.