Three people have died following a crash involving a car and a tanker truck on State Highway 1, about 5km north of Waiouru.
The crash happened between Shawcroft Road and Access Road No17, about 11.50pm.
All three occupants of the car died in the crash, while the driver of the tanker was treated for moderate injuries.
A helicopter was brought in to assist emergency service personnel with a search of the area to make sure nobody else was involved.
The loss of three lives is heartbreaking, says Whanganui Area Commander Inspector Neil Forlong.
"Our initial enquiries show the car has likely crossed the centre line just before the crash, but why that occurred is a focus of our investigation.
"There were initial fears a fourth person may have been travelling in the vehicle, but we have thankfully been able to rule that out.
"I want to acknowledge the fast response of emergency crews, who were faced with a tough scene.
"Crashes like this are devastating for the families involved and the community, and Police will continue to support those affected by this tragedy."
The Serious Crash Unit has carried out a scene examination and the road is expected to reopen this morning.
Enquiries into the cause of the crash are ongoing.
