Firefighters responded to the three-story building at 2445 Turk St. at about 5 p.m., a dispatcher at the San Francisco Fire Department said.
The dispatcher said the fire was contained in about 15 minutes.
Two trucks, three engines, two battalion chiefs, and several other firefighters assisted in containing the fire, he said.
The cause is still being investigated, and a damage estimate was not immediately available.
No injuries were reported.