Investigators are searching for the cause of an evening fire in a vacant residential building in Sandy Hill.

Emergency crews responded to calls for a working fire on Besserer Street, at Nelson Street, at approximately 7 p.m. Saturday. Multiple 911 callers reported smoke coming from the roof of the structure. 

Ottawa Fire photographer Scott Stilborn said the fire was located on the second floor of the multi-unit row house building, and in the roof areas.

No one was located inside the building.

An Ottawa Fire Investigator was on the scene Saturday evening to determine the cause of the fire.

Officials say a firefighter suffered "non-critical" injuries while battling the fire.