Firefighters are still on scene battling a three-alarm blaze on Osler Street that sent one person to hospital and caused an estimated $500,000 in damage Sunday evening.

“We’re trying to get the fire that is still smoldering in the attic. A lot of the roof has collapsed,” Div. Commander Bob O’Hallern told CP24 at the scene. “We still have crews up on the roof trying to get as close to the collapsed parts so they can put water on it.”

At 11 p.m. the street was still crowded with 18 fire trucks and 70 firefighters who had been called to the scene to battle the blaze.

Fire crews responded to a call about a two-alarm fire at 181 Osler St. near Davenport Road in the city’s west end shortly after 7 p.m. They found the home engulfed in flames when they arrived, and threatening to spread to four nearby homes.

The home was evacuated and paramedics transported one man to a local hospital to be treated for smoke inhalation. He was later identified as a tenant at 181 Osler St.

By 7:40 p.m. firefighters confirmed the blaze had been upgraded to a three-alarm fire.

Firemen on scene said it’s believed the fire started in the basement at 181 Osler St. and then spread up to the home’s attic.

Two homes – including the house where the fire originated – were heavily damaged, while two other homes were damaged as well, Toronto Fire said. It’s believed all are approximately 100 years old.

Firefighters on scene said new owners had just taken possession of 181 Osler St. on Monday. Firefighters also said a crew had been called to the same home on Feb. 7 because of a pot that had been left on the stove. They found the home had no working smoke detectors.

The Ontario Fire Marshall’s office has been notified because of the high cost of estimated damage.

The fire is not believed to be suspicious.

Pictures sent to CP24 by Twitter users near the scene showed smoke billowing up from the rear of the home.

Firefighters have not yet said what caused the fire.

Crews were expected to remain on the scene for several hours past midnight to ensure the blaze is completely put out.