A building located in the vicinity of Museum Drive and Highway 101 was damaged by a fire of undetermined origin early Independence Day.
Harbor and Brookings firefighters quickly stopped the blaze reported at 7 a.m. It started in a lower room of the two-story structure.
The heavy smoke could be seen for blocks.
A Harbor firefighter was injured and taken to Sutter Coast Hospital for an X-ray of his left knee.
Ben Bowers injured the knee shortly after the firefighters arrived, Chief Frank Kelley and Rob Smith said.
He entered the smoke-filled wooden structure, fell through the floor, and injured his knee.
Chief Kelley said he sent him to the hospital as a precautionary measure. There was evidence of swelling, Smith said.
A hospital spokesperson later said he was treated and released.
Smith described him as one of the best members of the department. He has a twin brother, Chris, who is also on the department.
Chief Kelley said the cause of the fire had not been determined, and that it would be referred to the state fire marshal for investigation. That is required for all fires that start in a n unoccupied building, the chief said.
The department said it had not determined the name of the owner of the building.