A 76-year-old woman is in hospital after firefighters found her passed out in hallway of a burning building in downtown Toronto.

The three-unit fire broke out shortly after 11 a.m. at 40 Poulett Street, near Parliament and Dundas Streets.

The woman had no vital signs when rescuers first found her, but was revived at the hospital.

Rescuers found the woman on the second floor and took her to St. Michael's Hospital, where her condition improved drastically within hours, said Toronto fire Capt. Mike Strapko.

"She suffered smoke inhalation but didn't appear to have any burns," he told CTV.ca on Monday afternoon.

Raymond Jewett, 44, was working in the area and rushed to the scene when he smelled smoke coming. After hearing cries coming from an upstairs floor, he wrapped himself in a sheet to ward off the heat and burst inside to help.

"The back draft threw me down the stairs," Jewett told CTV Toronto, saying when he opened the door many windows in the building burst "like a bomb."

"You've got to do what you've got to do," he said. "You've got to help a fellow human being out, straight up."

Firefighters were right behind him and rushed to get the woman to safety.

Strapko said the fire was extinguished by noon. Officials from the Fire Marshal's Office were expected on the scene in the afternoon to help determine the cause of the fire.

"It appears to have started on the second floor in a den," said Strapko, noting the building is a three-story townhouse and the injured woman was found on the second floor.

He said the third floor experienced significant smoke damage.

With a report from CTV Toronto's Chris Eby