A Taupiri man used "brute strength" to smash a truck window and free a trapped driver, a 41 year-old from Cambridge, after his freight truck tipped over on State Highway 1 south of Huntly this morning.

Grant Kiri was getting breakfast organised for his six children when he heard a noise, looked up and saw the freight truck tip over right in front of his property.

"It was really noisy and it just tipped up, there was smoke everywhere and I knew I had to get the truck driver out - that's what I would want someone to do for me," he said.

Kiri ran to the truck and could see the driver "stunned and dazed looking" on the passenger side of the cab.

"He had a big gash on his head and he looked pretty out of it - groggy so I smashed the window and pulled him out."

Oil could be seen covering the outside lane of the main Taupiri Roundabout at the corner of Gordonton Road.

Huntly Police constable David Simpson said it appeared the driver had not been wearing a seatbelt at the time of the crash.

"And that probably contributed to his injuries," Mr Simpson said.

The National Express freight truck had been travelling from Auckland to Hamilton carrying pet food and plastic when the crash happened about 7.45am.

The truck, which also brought down a power pole, was sprawled across the road and traffic was restricted to one lane while the scene was cleared.

- © Fairfax NZ News