A powerful earthquake that struck the heart of California's wine country caught many people sound asleep, sending dressers, mirrors and pictures crashing down around them.

The magnitude-6.0 quake struck at 3:20 am (6:20 pm China time) on Sunday near the city of Napa, an oasis of Victorian-era buildings nestled in the vineyard-studded hills of northern California.

Scores were injured as the temblor knocked out power to thousands, caused gas and water lines to rupture, and sparked fires.

By midday on Sunday, the fires were out and power was starting to be restored, said Mark Ghilarducci, director of the California Governor's Office of Emergency Services.

The quake struck about 10 km south of Napa and lasted 10 to 20 seconds, depending on its proximity to the epicenter, according to the US Geological Survey. It was the largest to shake the San Francisco Bay Area since the magnitude-6.9 Loma Prieta quake struck in 1989, collapsing part of the Bay Bridge roadway and killing more than 60 people, most of them when an Oakland freeway fell.

It was felt widely throughout the region, with people reporting feeling it 320 km south of Napa and as far east as the Nevada state border.

The quake's timing was also bad for Napa Valley's famed vineyards, where winemakers were just getting ready to harvest the 2014 crop. The quake broke thousands of bottles of wine and toppled barrels.

Vintner Richard Ward of Saintsbury Winery south of Napa watched on Sunday afternoon as workers righted toppled barrels and rescued a 225 kg grape de-stemmer that the quake had thrown to the ground.

"That's what happens when you're a mile (1.6 km) from the epicenter," said Ward, who lost 300 to 400 bottles in the winery's basement.

The grape harvest was supposed to start overnight on Monday, but it would now be pushed back a few days, he said. Had the harvest started a day earlier, the quake could have caught the workers among the heavy barrels when it struck, Ward said.

For many, the quake struck at the worst time possible, rousing them in the middle of the night and sending them fumbling in darkness to take cover and find loved ones. A number of the injuries were caused by people stepping on broken glass, falling down or being hit by furniture.

Omar Rodriguez, 23, of Napa, was treated for a gash on his forehead in one of the triage tents outside a hospital that handled the victims.

"We woke up to the earthquake and I thought I was dreaming because I fell off my bed, you know, it was all dark, and I just got back up. She noticed it was all bleeding," he said, referring to his girlfriend.

(China Daily 08/26/2014 page12)