Emergency responders pulled him from the rubble of the house following the Monday afternoon blast and paramedics said he was pronounced dead on the scene.
Toronto EMS duty officer Danny Antonopoulos said a person from an adjacent house was treated for minor hand injuries.
Fire Capt. Adrian Ratushniak said there was a severed gas line in the area, but couldn't say if the explosion caused the gas leak, or if the leak caused the explosion.
He said "numerous" homes in the immediate area were evacuated and the area was closed to traffic.
Ratushniak said firefighters have had to hold back their search until the gas leak has been stopped. Once that is done, they will continue to comb through the debris to search for others who may have been hurt in the explosion.
"There is just a hole in the ground," Ratushniak said. "But we'll be here all night until we have searched every inch of this place."
Photographs of the area by Toronto fire show nothing but rubble left from the house that stood two-storeys tall. Debris was scattered over hundreds of metres, some of it hanging from trees and on neighbouring houses.
Ratushniak said at least 12 other houses have been damaged and the Ontario Fire Marshal has begun an investigation.