Careless smoking is believed to be the cause of a fire that killed a 73-year-old man at an apartment building in King West Village early this morning.

It happened on Shaw Street, near King Street West, shortly after 3 a.m.

Toronto Fire Services Platoon Chief Kevin Shaw told CP24 that the fire broke out in a unit on the second floor of an apartment building located at 24 Shaw Street.

When fire crews arrived at the unit where it is believed the fire began, a man was found collapsed by the door.

“Crews arrived. There wasn’t any smoke showing initially. (They) proceeded to the second floor, where they were directed to apartment 215 and upon entry into the building, they located a victim that had apparently collapsed by the door," Shaw said at the scene.

"The crews brought him out immediately. They worked on him, tried to revive him. It was unsuccessful.”

Paramedics say the 73-year-old victim was pronounced dead at the scene.

Kevin Pahor, an investigator with the Ontario Fire Marshal, later confirmed that the fire originated on a couch in the living room after a cigarette was carelessly discarded.

The fire did not spread to other units and no other injuries were reported.

TTC buses were brought it to shelter the other occupants of the building who were evacuated.

Pahor added that a working fire alarm was in place and that the building was evacuated according to the building's fire plan.

Shaw said all residents have been allowed to return to their units.

Police have not released the name of the victim.

At the height of the fire, 12 trucks and 45 firefighters were on scene and the fire was knocked down at around 3:25 a.m.