A 6.0-magnitude earthquake shook this Northern California city early Sunday morning, sending dozens to the hospital, including at least three with major injuries, and causing major damage in wine country, prompting Gov. Jerry Brown to declare a state of emergency.

The quake, which hit around 3:20 a.m., was the largest to strike the area since 1989’s Loma Prieta quake. It left thousands without power as Napa officials sought to secure damaged buildings and repair water-line breaks and as business owners cleaned up.

Four mobile homes burned to the ground, a result of a gas-line break.

According to the U.S. Geological Survey, the South Napa earthquake originated within a 44-mile-wide set of major faults of the San Andreas system.

About 120 people were treated for injuries, mainly cuts and abrasions, while a young girl suffered severe injuries when a fireplace fell on her.

Gabe Haugen and Alexander McKenzie skated down Meadowbrooke Drive in Napa Sunday following a 6.0 magnitude earthquake in the San Francisco Bay Area. (Petula Dvorak/The Washington Post)

Residents braced for possible aftershocks during the next 24 hours that could further compromise buildings and cause more damage, particularly to wineries, which are key to the region’s economy.

A single wine glass survived at the Ceja Vineyards tasting room in Napa. The rest were shattered in piles that Ariel Ceja spent the day sweeping up.

“This? This is just stuff. The real question will be at the warehouse,” said Ceja, the son of vintners who have been growing grapes and making wine in the Napa Valley since 1983.

Like many vintners’ warehouses, theirs is closer to the epicenter of the powerful quake, where state highway workers quickly patched a huge crack in the road.

The 2014 vintage will be fine because the harvest season has just begun, and outside, “the vineyards just shake like this,” said Ceja, 31, with a little “Surfin’ USA” move.

Beyond the crumbled town library, shattered windows and broken possessions, the lasting effects of this quake for the region may involve the barrels and bottles of wine waiting to come to market.

“All of us are just waiting now to see how bad the damage is in all the warehouses, how much we lost from other years,” Ceja said.

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)

The wine industry generates about $13 billion in revenue for Napa County, attracting some 3 million tourists every year. On social media, people tweeted pictures of barrels and bottles overturned and gashes in roadways and in vineyard soil.

Just hours before the 3:21 a.m. quake, downtown Napa was packed with nearly 10,000 people for the Booze, Brews and BBQ festival.

“We’re all safe and sound because of when it happened,” said Amelia Moran Ceja, matriarch of the wine family. “A couple hours earlier and all that glass, bricks? It could’ve killed people. Imagine what Bacchus could’ve done to some,” she said, pointing to the one-ton statue of the god of wine that fell over and cracked at the entrance to their shop.

The damage to downtown Napa underscored how arbitrary earthquake damage is and how varied the ground beneath us must be.

Along First Street, the shattered storefronts were in a checkerboard pattern. Around the corner from Ceja, another tasting room didn’t lose a single bottle.

In the other direction, a knitting shop was a tangle of merlot-colored chenille and vine-hued wool.

“It’s all in one big pile,” said Randy Schwartz, who owns Yarns on First with his wife, Marcia.

His storefront was shattered, and at home, every drawer, cupboard and door opened up and spewed its contents forth. “I’ve never been through one like this before. It was the longest 15 or 20 seconds of my life,” he said. “But maybe it’s just God’s way of telling us we have too much [stuff].”

Downtown Napa was filled with gawkers who threaded through yellow crime-scene tape and picked their way around broken glass.

The weathervane on top of the 1874 First Presbyterian Church of Napa was cocked to the left. The glass in its soaring, neo-Gothic windows was shattered.

Bricks from the facade of Novelli Bail Bonds crushed a Nissan Sentra parked below, and the carved-stone curlicues from the Napa Library fell from its eves and littered the front steps.

The strips of car dealerships, big-box stores and groceries didn’t have such visible damage.

Throughout downtown, mothers pushed strollers, children rode bikes and everyone snapped selfies with the damage.

“How did you do?” they asked each other, and ticked off the glass shelves, vases, televisions and keepsakes that didn’t make it. It’s California, so everyone was in a pretty good mood. “It could’ve been worse,” they told each other.

The epicenter of the quake was buffered by miles of golden hills and patches of vineyards, an hour away from the roller-coaster hills of San Francisco. Still, the quake shook the city, and at 4 a.m., people were in the hallways of their buildings and in the streets, remembering the last big earthquake that hit the region, in 1989 — just as Game 3 of the World Series was kicking off in Candlestick Park.

The effects were felt as far away as Sacramento, considered by residents to be 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,” said Daniel Weintraub, who lives about 55 miles east of Napa. “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 up 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.”

Many of the damaged buildings are older, unreinforced masonry buildings that were not up to code, according to Napa city officials. They identified about a dozen structures as uninhabitable, while several others have broken windows and will have limited access.

A few roads buckled, yet the bridges were not damaged, according to city officials, who stressed that many of the repairs and would be complete in about a week and that many restaurants and businesses in this city of 80,000 were operating, even as schools were set to be shuttered Monday.

“Most of the Valley is operating as normal,” Mike Parness, Napa’s city manager, said during an afternoon news conference. He said he didn’t have a dollar amount for the damage. “The damage is in isolated locations, the issues are significant . . . but the conditions will vastly improve over the next few days as we get on top of this.”

Andreas Van Der Heyden, 73, said the temblor was unlike any he’d experienced before.

His wife, Darlene, said, “It was skitzy; it was violent.”

And seconds after the couple were tossed from their beds by the jolting and shaking, the orange of fire glowed through the window of their Napa Valley Mobile Home unit.

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.

Their home was singed and cluttered but didn’t bend and twist the way so many others did in the mobile home park, which looked like a blown-over house of cards in some spots.

And all the wine survived at the Van Der Heyden winery, up the road on Silverado Trail.

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

Darlene Van Der Heyden said they were relieved to have just delivered their shipment of white wines.

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

Henderson reported from Washington, Kindy from St. Louis. J. Freedom du Lac in Washington contributed to this report.