A woman in her 80s was slightly injured after a fire in her unit in a North York highrise building early Tuesday, Toronto paramedics say.

The fire generated heavy smoke and prompted several tenants to go outside until the smoke cleared.

District Chief of Toronto Fire Services Stephan Powell said the fire department received the call about the fire on the 17th floor in an apartment building on York Mills Road, near Parkwoods Village Drive and Victoria Park Avenue, at about 3:30 a.m.

When fire crews arrived, many tenants were in the stairwells as they tried to get out of the building.

"There was a tremendous amount of smoke on the 17th floor. There was a really heavy fireload in the unit," Powell said.

He said a lot of stuff in the unit caught fire. The fire primarily damaged the unit's second bedroom and a common area. The fire was brought under control in about an hour.

The cause has not yet been determined.

Powell said the woman, believed to be the sole occupant of the unit, was able to get out of the unit on her own but was treated by paramedics and taken to a local hospital.

About 25 firefighters and eight trucks responded to the call.

"We did our searches and found no one else there and no pets," he said.

"A good number of people sheltered in place and a good number of people self-evacuated."

Much smoke migrated to the 18th floor. An estimate of the damage to the unit was not available.