NAPA, Calif. (AP) - 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 on Sunday.

The 6.0-magnitude earthquake that struck just before 3:30 a.m. miles from Napa in California wine country was felt widely, breaking water mains, causing more than 100 gas leaks, leaving two adults and a child critically injured, damaging some of Napa Valley's famed wineries, and sending residents running out of their homes in the darkness.

Dazed residents too fearful of aftershocks to go back to bed wandered through Napa's historic downtown, where the quake had shorn a 10-foot chunk of bricks and concrete from the corner of an old county courthouse. Bolder-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 sounds from the earthquake was greater than my mom's screams," Rivera said.

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. Gov. Jerry Brown said in a statement that his emergency services office was working closely with state and local emergency managers to respond to residents and critical infrastructure that were affected.

The earthquake sent at least 87 people to Queen of the Valley hospital. Most patients had cuts, bumps, bruises, said Vanessa DeGier, spokeswoman for the Napa hospital. She says the facility has treated a hip fracture and heart attack, but it's unclear if it was related to the quake. The hospital has set up a triage tent and many people are still coming in, DeGier said.

Six significant fires, including at a mobile home park, Napa Division Fire Chief Darren Drake said. Four mobile homes have been destroyed and two others damaged, the city said. Several other smaller fires have been reported and firefighting efforts have been complicated by broken water mains.

The earthquake is the largest to shake the Bay Area since the 6.9-magnitude Loma Prieta quake in 1989, the USGS said. That temblor struck the area on Oct. 17, 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.

In Napa, three historic buildings have been damaged, including the county courthouse, and at least two downtown commercial buildings have been severely damaged. A Red Cross evacuation center has been set up at a high school and crews are assessing damage to homes.

"There's collapses, fires," said Napa Fire Capt. Doug Bridewell, standing in front of large pieces of masonry that broke loose from a turn of the century office building where a fire had just been extinguished. "That's the worst shaking I've ever been in."

Bridewell, who said he had to climb over fallen furniture in his own home to check on his family before reporting to duty, said he was starting to see more reports of injuries.

The shaking emptied cabinets in homes and store shelves, set off car alarms and had residents of neighboring Sonoma County running out of their houses and talking about damage inside their homes. Officials say widespread power outages have been reported in the area.

"It was a rolling quake, said Oakland resident Rich Lieberman. "It started very much like a rolling sensation and just got progressively worse in terms of length. Not so much in terms of shaking, but it did shake. It felt like a side-to-side kind of rolling sensation. Nothing violent but extremely lengthy and extremely active."

The USGS says the depth of the earthquake was just less than seven miles, and numerous small aftershocks have occurred in the Napa wine country.

"A quake of that size in a populated area is of course widely felt throughout that region," said Randy Baldwin, a geophysicist with the U.S. Geological Survey in Golden, Colorado. "The 6.0 is a sizeable quake for this area. It's a shallow quake. It's about 6 miles deep. We received hundreds of reports on our website from people that felt it in the surrounding area."

California Highway Patrol Officer Kevin Bartlett said cracks and damage to pavement closed the westbound Interstate 80 connector to westbound State Route 37 in Vallejo and westbound State Route 37 at the Sonoma off ramp. He says there haven't been reports of injuries or people stranded in their cars, but there are numerous flat tires from motorists driving over damaged roads.

Highway Patrol and the California Department of Transportation was checking roadways for damage, Bartlett said.

California Highway Patrol Officer Daniel Hill told KTVU-TV that road damage appears confined to the Napa and Sonoma areas. He said there appears to be no damage to major bridges in the Bay Area.

In Napa, city spokesman Barry Martin there has been significant damage. Store windows were broken and water mains broke in several locations, one of which left at least one street flooded.

___

Associated Press writer Tom Verdin in Sacramento contributed to this report.

Copyright 2014 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.