An investigation is continuing to determine the cause of a head-on crash south of Kawakawa that claimed one motorist’s life, critically injured another and led to widespread traffic chaos.

The accident occurred at 5.11pm on Tuesday on State Highway 1 about 50m south of the intersection with Waiomio Rd, when a tradie’s van and a small car collided.

Kawakawa fire chief Wayne Martin said volunteer firefighters from Kawakawa and Paihia brigades used cutting equipment to rescue the critically injured, and badly trapped, passenger from the van.

They also extracted the deceased driver and sole occupant from the car.

The driver of the van suffered moderate injuries.

Firefighters were at the scene for more than four hours, Martin said.

A significant road clean-up was required because the van was carrying a large amount of paint.

A specialist investigator from the police Serious Crash Unit attended and the scene was blessed by a local kaumatua.

A St John spokesman said three ambulances, one rapid response unit, one manager and one Northland Rescue Helicopter were sent to the crash.

One man was flown to Whangārei Hospital in a critical condition while the moderately injured patient was taken to Bay of Islands Hospital in Kawakawa by road.

It is understood the more seriously injured patient has since been transferred to Auckland.

SH1 was closed until 9.45pm, leading to significant delays for traffic travelling both to and from the Far North.

Two diversions were set up — one was a major detour via SH15/Mangakahia Rd and Kaikohe, while the other, in theory for light vehicles only, was via Ruapekapeka Rd.

The southern half of Ruapekapeka Rd is currently being widened and upgraded but the northern half, from Ruapekapeka Pā to Kawakawa, remains narrow, unsealed and unsuited to trucks or large volumes of traffic.

It’s believed a vehicle towing a boat came off the road but locals managed to tow it back on to the gravel.

Later, around 8.40pm, a milk tanker slid off the road, leaving both the Ruapekapeka Rd detour and SH1 blocked. The result was gridlock that continued late into the night.

Police advised motorists to avoid the area if possible.

A heavy haulage tow truck had to be dispatched from Whangārei to get the tanker back on to the road.

The highway reopened about 9.45pm.

Police will release the name of the deceased once all next-of-kin have been notified.

Tuesday’s fatality brings the Northland road toll for the year to date to 25, according to Ministry of Transport figures.