The fire was reported at 8:02 p.m. at a two-story building at 754 27th Ave., near Cabrillo Street. It was contained in about 30 minutes.
“There was quite a bit of fire showing when our crews arrived,” San Francisco fire department spokeswoman Lt. Talmadge said.
One man was transported to a hospital for treatment of smoke inhalation, Talmadge said.
The fire, which is believed to have been accidental, started outside, Talmadge said. Flames spread to the building and an adjacent structure.
The cause of the fire remains under investigation, and Talmadge did not yet have a damage estimate.