The fire broke out Wednesday after 2 p.m. at 19th Street and Vermont and firefighters were able to get the fire under control.
The two-story mixed use building that caught fire had offices on the lower levels and a single home at the top. The owner of the home was not home at the time of the fire.
People inside a dental office on the bottom level were quickly evacuated.
"Around 2:40, 2:45 this afternoon we received multiple phone calls for a fire around the area of 19th and Vermont. First arriving crews visualized a fire on the roof at 2210 19th Street," said San Francisco Fire Department spokesman Jonathan Baxter.
The owner of the home had gun powder in his residence, so he alerted firefighters of the potential danger.
The fire occurred across the street from a high school. There were few students inside because it was a shortened day, but the few who were there were told to shelter in place.
No injuries were reported. The cause of the fire is still under investigation.
HAPPENING NOW: Crews battling a fire in Potrero Hill neighborhood. pic.twitter.com/P7iRzJcEZS— Lyanne Melendez (@LyanneMelendez) September 21, 2016