Investigators are looking into the cause of an overnight fire that killed a father and son, and injured four others, including two family members.

Fire officials said an 82-year-old father and his adult son died in the blaze on Charrington Crescent, near Jane Street and Sheppard Avenue West.

The father's wife, believed to be in her 70's, and a second adult son, believed to be in his 40's, made it out of the house and were taken to hospital to be treated for smoke inhalation, police and fire officials said.

Two firefighters were injured while battling the blaze, which caused part of the main floor to collapse. One firefighter is believed to have suffered smoke inhalation, while the second suffered a minor leg injury.

Emergency personnel responded to the blaze when a neighbour called 911 shortly before midnight.

When firefighters arrived, the house was engulfed in flames and shrouded in smoke, and the windows had blown out. Outside, fire crews were greeted by the son who survived the blaze.

The man told firefighters three members of his family were inside the burning house, said Toronto Fire Services platoon chief Tony Bellavance.

Firefighters entered the home and rescued the mother, who was on the first floor, but they were forced to abandon the search for additional family members because of unsafe conditions within the house.

“Unfortunately they were driven out by the fire, things were too hot,” Bellavance told reporters at the scene. “They had to fight (from the) exterior for a little bit of time to get some control on the fire and then go back in and do a proper primary search.”

During that search, firefighters found one victim on the main floor and a second victim in the basement, where the fire is believed to have originated in a bedroom.

Occupant may have had mobility issues

Fire and police officials told CP24 at least one of the occupants may have had mobility issues because they found a walker inside the house.

It is not known if the occupants were alerted by smoke alarms, but neighbours said they heard the alarms before firefighters arrived.

“It wasn’t too distinct. I think at that time it was melting," said Vincenza, a neighbour.

Investigators have not confirmed if the alarms were functioning properly because the devices melted by the time firefighters swept through the house, fire officials said.

Investigators are planning to examine what's left of them to determine if they were working.

The Office of the Fire Marshal is investigating the cause of the blaze.

With files from CP24 reporter Cam Woolley

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