Thunder Bay Fire Rescue responded to an early morning fire on Friday.
Just after 2:30 a.m., crews were sent to a multi-unit residential building on John St. Road.
When crews got on scene they found smoke coming from a basement apartment and it was migrating to other parts of the home.
The homeowner of the affected apartment self-evacuated thanks to their smoke detector.
The building is a duplex and the neighbours were safely evacuated.
Fire crews were able to control the fire in the basement fire, preventing its spread to the adjacent residential unit.
A sweep of the building was performed to confirm nobody was left in the home.
At this time Fire Rescue believes the fire was related to a ventilation unit in the basement.