SAN FRANCISCO — A gas explosion set off a major fire in a San Francisco Bay Area neighborhood on Thursday after obliterating at least one home, blowing out windows and shaking nearby houses. Six people were taken to hospitals for injuries, fire officials said.

Alameda County firefighters on Thursday responded to an explosion and fire in an area densely populated with residential homes in a blast that destroyed homes, shut down a freeway and injured six people.

It's been less than a week since a massive explosion near Hayward after a construction crew hit a gas line, and now concerned neighbors are demanding answers from the Alameda County Board of Supervisors.

Investigators say a gas explosion caused the Rainbow Terrace fire, but what caused the blast and whether a gas leak led to it are still not clear.

Residents in the area said the explosion was thunderous, shaking their homes. They could hear the boom from the explosion and see the fire.

An explosion and fire rocked a Shell gas station at 16th and Guerrero streets in the Mission, sending smoke over San Francisco.