A woman is in critical condition after being pulled from a highrise fire in North York Wednesday afternoon.

Crews were called to a residential building on York Mills Road, east of the Don Valley Parkway, shortly before 2:30 p.m.

Toronto Fire said crews encountered smoke and heavy fire in a unit on the fifth floor.

They searched the place and located a female occupant without vital signs. She was immediately brought down, and crews performed CPR.

The victim, a woman in her 50s, was shortly rushed to the hospital with life-threatening injuries.

The fire reached a three-alarm response, but Toronto Fire said the bulk of the blaze had been knocked down.

The cause, origin and circumstance of the fire are unknown. Toronto Fire investigators will work with the Ontario Fire Marshal to determine what led to the blaze.

"We're in the preliminary stages. We're going to have to commence a comprehensive investigation, and part of that process will be doing a thorough examination of the scene, going through the debris to ascertain the origin and the ignition sources," Toronto Fire Deputy Chief Larry Cocco said.

When asked if there were smoking alarms in the affected unit, he noted that the scene was still being assessed.

Several residents had to be evacuated, and TTC buses were called to shelter them temporarily while crews worked on fully extinguishing the fire. Cocco did not provide the exact number of displaced residents.

He said there's some possible smoke and water damage in adjacent units.

"Right now, they're doing a comprehensive assessment of the floors below and above and on the same floor to see what units are re-occupiable," Cocco said.