An arterial route in Auckland has been reopened following a fatal collision between a car and a truck this afternoon.

The New Zealand Transport Agency said State Highway 1 was now opened to traffic in both directions between Warkworth and Wellsford in the Dome Valley after the incident which resulted in the death of a man.

A witness said a northbound car crossed the centre line and collided head-on with a flat-bed truck, about 7km south of Wellsford, just after 1pm. The deceased was an older man driving a black Holden Commodore.

Police confirmed one person died in a head-on crash.St John ambulance spokesman Robbie Walker said one other person was treated for minor injuries.


Another witness, Dillion Johnstone, was travelling southbound about 10 cars back from the truck when the crash occurred.

"His whole car door got ripped off - it was pretty gruesome. It pretty much swiped off the whole side of the car," Mr Johnstone said.

"It looks as though he just drifted across the centre line and crashed into an oncoming truck. The truck was carrying a caravan so it was probably around 6 tonne."

Mr Johnstone said traffic stopped immediately and people comforted the truck driver, who "was shaken but not injured".

The fatality was the second on New Zealand roads today.

This morning, Nathan "Blackie" Walters, 70, of Northland died in a crash involving a car, a ute and a school bus.

It happened shortly before 8am on State Highway 12, south of Mamaranui, north of Dargaville.

The Northland Rugby Union, for which Mr Walters was a volunteer, later paid tribute to a man "who always had a smile on his face".

"Blackie will be deeply missed as he was a tireless volunteer who always had a smile on his face, was available any time to drive the bus transporting club and Northland rep teams to fixtures throughout and province and wider afield," the union wrote on Facebook.

Another person was seriously hurt in this morning's crash, but all the children on board the bus escaped uninjured.

Meanwhile, a woman who was critically injured about 7am yesterday in a head-on crash south of Dunedin died today in Dunedin Hospital.

She was Holly Ann Watt, 20, of Milton.

Ms Watt's black sedan appeared to cross the centre line at Henley and crashed into a northbound ute being driven by a 50-year-old Balclutha man. He suffered moderate injuries.

A serious crash unit investigation is ongoing.N