At approximately 1:17pm firefighters responded to a house fire in the 900 block of Tazewell Ave. When crews arrived they had heavy smoke and flames coming from the back of the 2 story house. One firefighter sustained non-life threatening injuries when he partially fell through the floor. His fellow firefighters helped him escape the home. He was transported to Carilion Roanoke Memorial Hospital for observation but is expected to be ok. The house was vacant and no one was inside when the fire started. The fire was intentionally set and the investigation is ongoing. The house sustained extensive damage. A damage estimate isn’t available right now. If anyone has information about the fire, please call the Roanoke Fire Marshal’s Office at 540-853-2795.