Senior Constable Kelvin Cox said it appeared from an initial scene examination the southbound car collided with the empty logging truck which was travelling north.
Cox said the car may have been attempting to turn right into Raumanga Valley Rd.
The driver had to be cut free from the car by firefighters and was taken to Whangārei Hospital in a serious condition.
A male front-seat passenger was able to free himself and was also taken to Whangārei Hospital with moderate injuries.
Mangonui Haulage logging manager Darren Brott confirmed a company truck was involved in the crash.
He said his driver was travelling northbound on State Highway 1, without a load, when a southbound car slipped onto his side of the road collided with the truck.
The driver was shaken up from the experience but had not been injured, he said.
The truck, as he understood, had been significantly damaged.
NZTA advised motorists to consider using SH14 and SH15 around the accident until the road reopened at 8.50am.
The crash is near the scene where a car crashed into a power pole in October last year which closed the road for several hours.
Power was out to 480 properties after two lines, an 11,000-volt and a 400-volt one, came down in the crash. Remarkably, no one was injured.
A car, which had earlier fled police, also crashed at the intersection in December 2017 resulting in several injuries and closing the main arterial access road for several hours during the afternoon commute.
