A truck has crashed into a power box outside Liquorland on the intersection of Redwood St and Kinross St, in Blenheim.

A vet in Blenheim has been forced to finish off a surgery by torchlight after a truck crashed into a power box, cutting power to nearby businesses.

The truck driver was turning out of the Liquorland car park on the corner of Redwood St and Kinross St, in Blenheim, when it mounted the footpath and crashed into a power box.

The crash caused a partial power outage to the liquor store and The Vet Centre across the road, where a vet was halfway through surgery on a dog.

A vet clinic spokeswoman said the vet had no choice but to finish the surgery by torch.

"We were able to finish the surgery using an old oxygen bottle and a stethoscope for monitoring. There was no danger to the dog at any point, we just had to go back to old-fashioned ways of doing things."

The tills were not working while the power was off, so the clinic had to turn several customers away, the spokeswoman said.

SCOTT HAMMOND/STUFF Marlborough Lines workers check out the damage to the power box under the truck.

Havelock woman Annette Black came into town to take her shitzu maltese Bella for a haircut, only to find a few missed calls on her cellphone when she arrived, and the office plunged into darkness.

"It is a bit inconvenient," Black said, heading out the door.

"They tried to ring me but I don't pick up when I'm driving. I think I'll just go home and come back next week."

SCOTT HAMMOND/STUFF The crash cut power to businesses along Kinross St, in Blenheim.

The truck was blocking the westbound lane and police diverted traffic down Freswick St.

Senior Constable Tony Barrow said police were still determining the cause of the crash, but it appeared the truck driver took a sharp left-hand turn and its rear wheels crashed into the power box just before noon on Tuesday.

Liquorland owner Warren Dillon said he saw the crash through the store window.

"He tried to drive off the box, he went forward and then he went backwards but it was just causing more damage so he stopped," Dillon said.

"The back wheels never follow the front wheels on a truck that long."

The driver declined to comment.

Marlborough Lines turned the power off to the box about 15 minutes after the crash, and Dillon had been unable to serve customers while the tills were off, he said.

A Marlborough Lines worker said getting the truck off the power box would be the "easy part".

"It's going to be a big repair job."