An earthquake with a magnitude of 6.0 struck the San Francisco Bay area early Sunday, prompting California Gov. Jerry Brown (D) to declare a state of emergency. The earthquake hit just before 3:30 a.m. Pacific time about 10 miles northwest of American Canyon, which is about six miles southwest of Napa, in California’s wine country, according to the U.S. Geological Survey.

Widespread damage — to historic buildings, to wineries, to residences — was reported throughout the Napa Valley following the largest earthquake to shake Northern California since the devastating 6.9-magnitude Loma Prieta temblor in 1989. Using automated economic-loss software, the USGS estimated that damages from Sunday’s earthquake are likely to surpass $1 billion.

More than 150 people were treated at Queen of the Valley Medical Center on Sunday, hospital officials said, but not all of the injuries were directly related to the earthquake.

There were several major injury cases, though, including a child who was in critical condition after a chimney collapsed. The 13-year-old was airlifted from a Napa hospital to a trauma center, the San Francisco Chronicle reported.

President Obama was briefed on the earthquake, the White House said, and federal officials are in touch with state and local officials.

In Napa, dozens of historic buildings were damaged, and crews responded to numerous gas line breaks and water main leaks, according to city officials, who said repairs would take about a week.

The seismic strength of every earthquake gets calculated based on a now universal magnitude scale. Here's where that scale came from and how it works. (Gillian Brockell and Kate M. Tobey/The Washington Post)

Four homes at a mobile-home park were destroyed by fire after the quake.

“It was violent,” said Darlene Van Der Heyden, who said she and her husband, Andreas, were tossed out of bed when the earth began to move. (The USGS estimated that the earthquake lasted between 10 and 20 seconds.) Moments later, the Van Der Heydens said, the orange of fire glowed through the window of their Napa Valley mobile home.

They screamed to their neighbor, and she got out in time. But her mobile home was one of four that burned to the ground, leaving behind a charred metal skeleton and the shell of a car. It looked like a fire and explosion in a war zone.

The Van Der Heydens’ mobile home was singed by the fire and cluttered by the earthquake, but it didn’t bend and twist the way so many others did in their mobile-home park, which looked like a blown-over house of cards in some spots.

And all of the wine survived at their winery, up the road on Silverado Trail.

“We stack the barrels only two or three high,” Andreas Van Der Heyden explained. “Not five or six high, like some others do.”

His wife said they were also relieved to have just delivered their shipment of white wines.

“Our whites were gone, delivered, out of here and safe,” she said.

Vanessa deGier, a spokeswoman for Queen of the Valley Medical Center, said most patients treated at the hospital had minor cuts, bumps and bruises, and were treated and released. She said the facility had treated a hip fracture and a heart attack, but it was unclear whether they were related to the earthquake. Queen of the Valley sustained earthquake damage itself; at least one window at the hospital was shattered, according to a reporter from KRON-TV.

City fire and police officials said during a news conference that there was relative calm as they worked on securing the downtown Napa area and identifying the most damaged structures. At least 15 buildings were “red-tagged” by the city.

Napa is wine country, with related tourism bringing in $1 billion annually and drawing 3 million visitors each year. The wine industry, hit hard by the earthquake, has a $13.3 billion annual economic impact on Napa County, and many of the images flooding social media and news accounts show busted bottles and overturned shelves.

Jay Jacobs, who lives on and owns the Cuttings Wharf Vineyard in Napa, called the area a disaster.

“We have no electricity. Lines are down everywhere. It knocked over a cabinet filled with clothes,” said Jacobs, who grows Chardonnay grapes on his 16 acres. “A TV was knocked off the stand. All the pictures flew off the wall.”

He said he does not think there is damage to his home, which was built about 20 years ago, or his vineyard, which is about seven miles south of downtown Napa.

But other wineries didn’t escape damage:

Daniel Weintraub, who lives about 55 miles east of Napa, said he has felt a number of earthquakes, including Loma Prieta in 1989. But he couldn’t recall being awakened by an earthquake in Sacramento, considered an “earthquake-free zone.”

“It woke me up. The house shook for at least 10 seconds after I realized what was happening, multiple shakes like wind gusts, but much stronger,” Weintraub said. “Since we almost never have earthquakes in Sacramento, I guessed immediately that this was a strong one, in either the Bay Area or the Sierra.”

Others had similar stories of being woken in the middle of the night by the earthquake, which to some sounded like an oncoming freight train.

“Everything came off every single shelf. Every picture was off the wall. Every dish had come out of the cabinet and was broken on the floor,” said Chris Cox, 40, who conducts wine tours for a living and works at Napa Valley Caterers as a bartender. “The refrigerator opened and most of the food was out on the floor. Everything that was in bottles was broken, and food was all over the place.”

Cox, who was about two miles north of downtown Napa and five miles south of the epicenter, said  people who live in the hills of Napa, which is made of rock, versus the valley floor, which is made of clay, seemed to fare better.

Surveillance video from an RV park in Vallejo, not far from the epicenter, showed the moment the 6.0-magnitude earthquake struck.

Surveillance video from the Tradewinds RV Park in Vallejo, Calif., shows the moment the 6.0-magnitude earthquake struck northern California early Sunday. (Facebook/Monica Alvarez)

The earthquake lies within a 44-mile-wide set of major faults of the San Andreas fault system, according to the USGS.

Napa City Manager Mike Parness stressed that although there is damage and about 20,000 residents remain without power in this city of 80,000, lots of restaurants and businesses are still open and serving the community. “Most of the valley is operating like normal,” he said at an afternoon news conference. “The damage is in isolated locations…. The conditions will vastly improve over the next days.”

Two professional games were scheduled for Sunday in the area: The San Diego Chargers played the San Francisco 49ers in the afternoon and the Los Angeles Angels were visiting the Athletics in Oakland at night. Both games are well south of the quake area. The Loma Prieta earthquake struck just before the start of Game 3 of the World Series between the San Francisco Giants and the Oakland A’s in San Francisco. An IndyCar Series race scheduled for Sunday in Sonoma ran as planned.

A large earthquake jolts California’s northern Bay Area early Sunday, damaging some buildings, knocking out power to thousands and sending residents running out of their homes in the darkness. (Reuters)

Petula Dvorak in Napa and Cindy Boren in Washington contributed to this report.

[This post has been updated multiple times.]