A three-alarm fire near San Francisco’s Civic Center was quickly extinguished Sunday thanks to the help of police officers.

About noon, police Sgt. William Conley and another officer were driving on Golden Gate Avenue when they noticed black smoke billowing from the roof of 370 Golden Gate Ave.

“We knew something wasn’t right,” Conley said.

The fire came from a ventilation duct at Taqueria El Castillito, which occupies the bottom floor of the building. Conley said he and the other officer called for backup, then immediately went into the five-story building to help get out as many people as possible.

According to police Lt. Colleen Fatooh, Conley helped as many as 50 people leave the building. No injuries were reported. Damage estimates to the building and taqueria were unavailable as of press time.

The fire was contained less than an hour later.

akoskey@sfexaminer.com