Firefighters battled flames for two hours Saturday evening around 9 p.m. while trying to keep the fire from spreading.
The Victorian home at Utah and 25th streets was severely damaged. A neighboring home had minor damage as well.
Firefighters, at one point, were concerned that the entire block might burn given the close proximity of the homes on the street.
"Our company made a quick, very aggressive interior attack," said San Francisco Fire Department Chief Tom Siragusa, adding that about 20 companies and over 100 firefighters battled the blaze.
Traffic on nearby Highway 101 was affected as smoke drifted onto the freeway.
There were no injuries.
