The Tenderloin fire was reported at 8:56 p.m. Tuesday at the Franciscan Towers, a 105-unit residential hotel at 217 Eddy St., fire officials said.
The three-alarm blaze injured 22 people, displaced more than 100, and caused more than $1 million in damage, Deputy Fire Chief Pat Gardner said.
The fire apparently started in a trash compactor in the building's basement and spread through the building via its garbage chutes, Gardner said.
The cause of the fire remains under investigation, Talmadge said. The next night, another three-alarm fire was reported, this one at a building at 3212 Mission St., near Valencia Street.
The fire, reported at about 8:10 p.m., Wednesday spread to two adjacent buildings before it was controlled about two hours later, Gardner said.
A firefighter was injured while battling the blaze. He was on a ladder and hosing the fire down when he fell about eight feet to the ground, Gardner said. He was taken to San Francisco General Hospital with a back injury.
The three-story building where the fire started contains a dental office on the first floor and apartments above it.
The other two buildings affected by the fire were also mixed-use buildings, Gardner said. One houses the Lotus Garden Vietnamese restaurant, and the other contains the Los Panchos Mexican restaurant.
An employee at Los Panchos said the business only sustained minor damage, to doors that had to be broken by firefighters.
Gardner said that fire caused about $1 million in damage to the three buildings and their contents.
About 12 people were displaced by that fire, although residents were able to return to the apartments above the Mexican restaurant the next day, Gardner said.
The American Red Cross is assisting residents displaced by both fires.