Firefighters rushed into the 12-unit building on 26th Street between Mission and Valencia when they heard there may have been a person inside. It turned out that everyone had made it out okay, but the fire was seriously-involved when crews arrived at 2:30 p.m.
One woman, her daughter and her grandson all got out okay, but were upset they had to leave behind the ashes of the women's husband. Fortunately, firefighters were able to go back in and get them. One pet cat was killed in the fire.
"It's probably the most intense thing that's ever happened to me. It was terrifying," said resident Kate McCarthy.
"It was just adrenaline and sadness, and then happiness because we're alive," said resident Marcos Pacheco. "But, definitely, I'm devastated. But, what can I do?"
The fire burned through the roof of the building and heavy black smoke could be seen for miles. Firefighters were at the scene until after 6 p.m. Sunday boarding up the building and looking for clues.
One firefighter was taken to a hospital suffering from chest pain and is expected to be okay.
The cause of the fire is under investigation.