The Ontario Fire Marshal's office is continuing its investigation into the cause of a fatal fire that killed one resident and displaced more than 100 others at a seniors' home in Ottawa's east end last week.

Seventy-three-year-old Gaston Charbonneau, who lived in the third floor room where the fire apparently started, was pronounced dead at the scene. Four other residents were treated for minor smoke inhalation.

While the blaze forced 121 residents out of Rothwell Heights Terrace on Thursday, those living on the first and second floors were able to return home Saturday night. Officials say the third floor remains closed until it undergoes renovations.

Although there is no word on the official cause of the blaze, the building's owners said they believe smoking was the cause.

Co-owner Dorothy Vlaming told CTV Ottawa last week that Charbonneau had been reprimanded several times for smoking in the non-smoking building.