The massive blaze occurred at a vacant building near the campus of Ryerson University in the city's downtown near Yonge and Dundas Streets just after 4 a.m.
Fire officials sent out a Mayday alert shortly after 5:30 a.m. after the two firefighters slipped from the roof of an adjacent building when wind gusts sent thick smoke and debris towards them. A PostMedia News report said they fell more than 20 feet before landing in the flames.
The department's RIT team pulled the two men from the fire and they were quickly transported to a local hospital.
Two of the members of the RIT team were injured. One was transported to the hospital as a precaution and the other injured his hand and was treated at the scene.
Three hospitalized firefighters were released in good condition, according to reports.
As many as 32 trucks and 125 firefighters were called to the scene of the blaze and five aerial towers were used to help douse the blaze.
Capt. Mike Strapko told CTV that the fire was still being brought under control at 8 a.m.
"We've got the upper hand now, so it's just a matter of time," he said. "The building is structurally unsafe so we can't go inside. There is going to be fire hiding in rooms or in ceiling and behind walls. We are going to be here for a while."
The century-old building -- which was recently declared a heritage site -- has a history of being unsound and had a wall collapse last April.
