The one-alarm fire started at about 5:20 a.m. in the back of the building at 790 Brannan St., spokeswoman Mindy Talmadge said.
The address is listed as Oscar’s Photo Lab.
Responding crews discovered thick smoke, and had the fire under control about 30 minutes later.
“There was quite a bit of fire in the rear of the building that was difficult to get to,” Talmadge said.
She said the photo lab butts up against a concrete building, which prevented the fire from spreading.
A damage estimate was not immediately available, and the cause is still under investigation, Talmadge said.
Janna Brancolini, Bay City News
5:48 AM: San Francisco firefighters are on the scene of a one-alarm fire in the South of Market District, a fire dispatcher said.
Firefighters responded to reports of a fire at Brannan and 7th streets at 5:22 a.m. and were still on the scene as of 5:45 a.m., the dispatcher said.
No further information was immediately available.