An 83-year-old pedestrian is in critical condition after a collision with a garbage truck in Dartmouth, say Halifax Regional Police.

The collision happened Thursday at about 2:15 p.m. at the intersection of Maynard and Portland streets.

"What we have is an 83-year-old woman that somehow ended up under the wheels of a garbage truck. She was rushed to hospital by EHS with very serious injuries," said Halifax Regional Police Const. Pierre Bourdages.

Tony Sanderson told CBC News he saw the accident while driving on Maynard Street.

Tony Sanderson

Tony Sanderson saw the collision while driving on Maynard Street. (CBC)

"I saw an elderly lady run out of her house to put some garbage in the garbage truck and not knowing she was there, the garbage truck had rolled ahead and unbeknownst to them had knocked her down," he said.

"He pulled over at the next garbage stop and had pinned her under the tire."

Sanderson said the driver had no chance to see the woman, who was on the ground quickly.

He said when the truck stopped, the woman's foot was under the rear wheel. When the driver came out and saw the woman, he immediately moved the truck forward to free the woman's foot, said Sanderson.

He said other witnesses responded immediately. Sanderson called 911 and two women began first aid.

Police are asking people to avoid the area.