The largest earthquake to hit the San Francisco Bay Area in 25 years sent scores of people to hospitals, ignited fires, damaged multiple historic buildings and knocked out power to tens of thousands in California’s wine country on Sunday.

The magnitude-6.0 earthquake that struck at 3.20am, about six miles from the city of Napa, ruptured water mains and gas lines, left two adults and a child critically injured, upended bottles and casks at some of Napa Valley’s famed wineries and sent residents running out of their homes in the darkness.

President Barack Obama was briefed on the earthquake, the White House said. Federal officials also have been in touch with state and local emergency responders and Governor Jerry Brown declared a state of emergency for southern Napa County, directing state agencies to respond with equipment and personnel.

“This was a pretty big jolt in Napa, but it certainly is not ‘The Big One’,” Barry Martin, Napa’s community outreach co-ordinator, said in comments to local television, referring to fears Californians have of a catastrophic quake along one of the seismic faults underneath the state.

California is forecast to experience a much more powerful earthquake at some point, but scientists do not know exactly when it will come or how strong it will be, said a US Geological Survey geophysicist, Don Blakeman.

“Usually when people talk about ‘The Big One,’ they’re talking about something on the order of a magnitude 9, which of course is tremendously more powerful” than Sunday’s quake, Blakeman said.

Dazed residents too fearful of aftershocks to go back to bed wandered at dawn through Napa’s historic downtown, where the quake had shorn a 10ft chunk of bricks and concrete from the corner of an old county courthouse. Boulder-sized pieces of rubble littered the lawn and street in front of the building and the hole left behind allowed a view of the offices inside.

College student Eduardo Rivera, 20, said the home he shares with six relatives shook so violently that he kept getting knocked back into his bed as he tried to flee.

“When I woke up, my mom was screaming, and the sound from the earthquake was greater than my mom’s screams,” Rivera said.

A building is seen destroyed in Napa. Photograph: Justin Sullivan/Getty Images

Napa fire operations chief John Callanan said the city has exhausted its resources trying to extinguish six fires, some in places with broken water mains; transporting injured residents; searching homes for anyone who might be trapped; and answering calls about gas leaks and downed power lines.



Two of the fires happened at mobile home parks, including one where four homes were destroyed and two others damaged, Callanan said.

The earthquake sent at least 87 people to Queen of the Valley Medical Center in Napa, where officials set up a triage tent to handle the influx. Most patients had cuts, bumps, bruises, said Vanessa DeGier, a hospital spokeswoman. Callanan told the Associated Press the young child had been struck by part of a fireplace and airlifted to a specialty hospital for a neurological evaluation.

The earthquake is the largest to shake the Bay Area since the magnitude-6.9 Loma Prieta quake in 1989, the USGS said. That temblor struck the area on 17 October 1989, during a World Series game between the San Francisco Giants and the Oakland Athletics, collapsing part of the Bay Bridge roadway and killing more than 60 people, most when an Oakland freeway fell.

Sunday’s quake was felt widely throughout the region. People reported feeling it more than 200 miles south of Napa and as far east as the Nevada border. Amtrak suspended its train service through the Bay Area so tracks could be inspected.

Napa city manager Mike Parness said at an afternoon news conference that 15 to 16 buildings were no longer inhabitable, and there was only limited access to numerous other structures, mostly ones with broken windows. Officials said they were still assessing buildings in the area.

Facebook Twitter Pinterest A truck navigates around a buckled section of California’s Highway 12. Photograph: Peter DaSilva/EPA

A Pacific Gas and Electric spokesman, JD Guidi, said close to 30,000 people lost power right after the quake hit, but the number was down just under 19,000, most of them in Napa. He said crews were working to make repairs, but it was unclear when electricity would be restored.

The depth of the earthquake was just less than seven miles and numerous small aftershocks have occurred, the US Geological Survey said.

“A quake of that size in a populated area is of course widely felt throughout that region,” said Randy Baldwin, a geophysicist with the USGS in Golden, Colorado.