The occupants of the car that hit and injured at least two pedestrians in central Christchurch this morning were "absolutely hysterical", according to a witness.

The witness told Newshub the mother and high-school aged daughter in the vehicle were in shock.

"Neither could be calmed down, they were horrified about the whole thing."

The witness, who did not want to be named, believed the pedestrians were crossing the road at the time of the accident.

Police told Newshub the incident happened on the corner of Fitzgerald Ave and Gloucester St just before 9am. The car hit a light pole and at least two pedestrians.

St John Ambulance took a woman to Christchurch Hospital with critical injuries. Two others were treated at the scene, one with moderate and one with minor injuries. Newshub understands one of the injured was an occupant of the vehicle.

Mechanic Jacob Withers says he was working nearby when he heard a car "revving the full amount of revs it could rev at", followed by a loud crash.

"I'm guessing the throttle got jammed somehow, and the car took off," he said.

Mr Withers said he heard people screaming in the car as well as outside, and there was "a lot of panic".

He went outside and saw "a couple of people lying on the ground".

"There were people everywhere helping the people that were lying on the ground, and a couple with the people in the car, trying to help them and calm them down."

Newshub.