The fire was reported at 11:21 p.m. at Bethany Center Senior Housing, located at 580 Capp St., San Francisco fire Lt. Mindy Talmadge said.
Firefighters responded and controlled the blaze by 11:38 p.m., Talmadge said.
One person was treated at the scene for smoke inhalation but did not require hospitalization, she said.
The fire damaged one unit at the center, but a damage estimate was not immediately available this morning, Talmadge said.
The cause of the blaze is under investigation.
Dan McMenamin, Bay City News