NAPA, Calif. — Early Sunday morning, Franz Oehler's house blew apart.
"My girlfriend and I were thrown straight in the air, and the windows exploded," said Oehler, a 44-year-old creative director, whose home is nestled among some of the country's most celebrated vineyards.
A magnitude-6.0 earthquake hit the Napa Valley at 3:20 a.m. Sunday — the strongest temblor in the San Francisco Bay area in a quarter century — destroying both opulent and modest homes, rupturing dozens of water and gas mains, and causing injuries — mostly minor — to more than 100 people.
Gov. Jerry Brown declared a state of emergency and directed state resources toward a recovery effort in Napa. President Barack Obama was briefed on the earthquake, the White House said, and federal officials were in touch with state and local emergency responders.
At least 120 people had been treated at the emergency room at Queen of the Valley Medical Center in Napa, said Vanessa deGier, a hospital spokeswoman. Most of the injuries were minor lacerations or abrasions caused by falling debris. But three patients were in critical condition, including a child who had been crushed by a falling fireplace. No deaths had been confirmed as of Sunday evening.
The shaking was felt as far away as Salinas, and the U.S. Geological Survey estimated damage could be up to $1 billion.
U.S. Rep. Mike Thompson, who represents Napa, said federal and state officials had conducted an aerial survey of the area, but wouldn't have a cost estimate for the damage until they can get on the ground and into buildings. He said while Napa suffered the worst of it, there also was significant damage about 17 miles south on Mare Island in Vallejo, a former naval shipyard where a museum and historic homes were declared uninhabitable.
Despite the widespread damage, scientists said California was fortunate to escape greater devastation from the earthquake, which exposed gaps in the state's preparedness. The historic 1906 San Francisco earthquake was about 500 times larger than Sunday's temblor.
"It is truly small — small compared to what California has experienced in its recorded history," said Ross Stein, a geophysicist at the U.S. Geological Survey.
"We owe wine country in part to earthquakes," which created the Napa Valley terrain that is so suitable to vineyards, he said. "We all want to enjoy the fruits of the quakes, so we all have to prepare for the downside, too."
However geologically small, the earthquake unleashed chaos in many parts of the Napa Valley, a serene escape known for its fine dining.
At Oehler's home, a skylight shattered and stone sculptures flew into the air. The swimming pool cracked open, flooding his steep hillside. "There was noise everywhere from the earthquake and the walls cracking," he said.
From the terrace he said he saw flames rising in the valley below.
Several fires broke out after the earthquake, including one at a mobile home park that destroyed six homes, the authorities said.
Two residents of the park, Lynda and Bob Castell-Blanch, both 60, were jarred awake by a loud thump, followed by rolling. The mobile home park where they lived soon shot up in flames.
"It was violent," Bob Castell-Blanch said. "Things were flying all over the place. There was a woman screaming from one of the houses, so loud it was total mayhem."
Because a nearby water main had ruptured, however, firefighters were unable to tap into the hydrant to fight the fire, and had to truck in water from elsewhere.
The couple said they had enough time to gather their cats and vintage guitars before fleeing. "That was all we had time for," Castell-Blanch said.
They went to a nearby store, the Ranch Market, to try to buy water, but the shelves had been emptied. The smell of wine from broken bottles wafted through the store.
Arik Housley, the store's owner, estimated at least $100,000 in damage at the two markets he owns in the area. Like many people, he said he did not carry earthquake insurance because the premium was high.
By Sunday evening, more than 10,000 people remained without power, and parts of the city still smelled of natural gas. About 600 homes were without water.
Much of the heaviest damage was in downtown Napa, where large sections of brick had fallen from the county courthouse and other historic buildings. Three of the buildings that sustained severe damage had not been retrofitted to withstand earthquakes, city officials said, while the retrofits on some other older buildings did not hold, and large sections of brick and concrete collapsed onto the sidewalks.
More than 30 buildings across the city were deemed uninhabitable.
"Certainly, a few of the retrofits didn't fare that well," a Napa County supervisor, Mark Luce, said. He added that many more buildings, including the county administrative building, had interior damage including broken sprinkler lines and fallen ceilings that would be costly to repair. "The newer buildings that met current standards fared better, but there's still a lot of mess to clean up inside," he said.
"We'll look at what happened with these couple buildings where we saw these failures, and see if there's anything we missed," Luce added. "We've had a live test of what a 6.0 earthquake will do."
Kelly Houston, a spokesman for the California Emergency Management Agency, said the quake was also a reminder that the entire state — not just Los Angeles and San Francisco — were at risk.
"This is definitely a wake-up call, especially for the people in Napa Valley," Houston said. "Maybe folks there think they don't have to worry as much because they don't live in San Francisco."
In the hills outside this city, winemakers like David Duncan, whose family owns the Silver Oak winery, rued the loss of "irreplaceable" wine that fell from the shelves in one of its cellars.
"It was everything — hundreds of bottles broke," he said.
Oehler, the creative director, picked his way through shards of marble and glass, counting an irreplaceable loss, his home.
"We spent a lot of money and love on this place," he said. "It's all gone now. It's cracking and sliding down the hill."
Information from the Associated Press was used in this report.