A woman has been taken to Whangarei hospital in a serious condition after a collision with a fully laden concrete truck.
The crash happened just after 9am in the passing lanes on Lookout Hill, only a few kilometres south of Whangarei.
After a preliminary scene examination police at the scene said it may have been a passing manoeuvre that went wrong.
The female driver of a northbound vehicle had to be cut free by firefighters after her Toyota car collided with the southbound concrete truck. The driver of a second northbound car was not injured and could drive from the scene.
The truck driver was shaken but not injured. A tow truck was used to pull the concrete truck back on the road. State Highway 1 was opened again about 11.30am.