A quick-thinking neighbour alerted Calgary firefighters to a fire in the northeast community of Castleridge on Thursday.
Crews arrived at the home on Castlebrook Way N.E. around 1:20 p.m. to find thick black smoke coming from the windows.
They immediately entered the home and determined no one was inside. Investigators are still trying to contact the homeowners.
Carol Henke, with the Calgary Fire Department, said there was damage to the basement and smoke damage throughout the home.
As of Thursday afternoon, fire crews remained on scene monitoring hot spots.
Henke said it is unclear if the smoke detectors were working at the time, but said when crews arrived they had melted from the heat.
No word yet on what caused the fire.