The fire was reported at 6:08 p.m. at 66 Rondel Place, an alley off of 16th Street between Mission and Valencia streets.
More than 100 firefighters battled the flames and brought the fire under control at about 7:45 p.m., fire department spokeswoman Lt. Mindy Talmadge said.
Three firefighters suffered minor injuries and were taken to hospitals. Two civilians were also injured and were transported to a hospital.
The fire department initially tallied 43 people who were displaced, but an American Red Cross spokeswoman said this morning that number appears to be closer to 20.
The Red Cross is assisting two families who need help finding shelter, spokeswoman Patricia Peper said.
The fire caused about $900,000 in damage to the building where it originated and $212,000 in damage to its contents, Talmadge said.
A building at 72 Rondel Place sustained $170,000 in content and structural damage, and $90,000 in damage was tallied at 64 Rondel Place.
The blaze also caused $120,000 in structural damage and destroyed an estimated $120,000 in contents at a building that houses 571 and 577 Valencia St., Talmadge said.
The cause of the fire has not yet been determined but investigators consider the blaze suspicious, Talmadge said.