A preliminary magnitude 6.0 earthquake rocked the San Francisco Bay Area early Sunday morning, centered in the Napa County town of American Canyon, but felt across Northern California.
The Napa County region is reporting the worst damage so far, reports CBS San Francisco. Dozens of aftershocks in the area have been reported since the quake initially struck overnight.
Officials there so far have reported dozens of injuries. Reuters reports at least two of them were serious, although details are still coming in.
One hospital in the Bay Area reports it has treated more than 70 patients so far injured by the quake.
Vanessa DeGier, spokeswoman for Queen of the Valley hospital in Napa, told the Associated Press most of those were treated for cuts, bumps and bruises. She said the facility has treated a hip fracture and heart attack, but it's unclear if it was related to the tremor.
The Napa city government told Reuters there were 50 gas main breaks and 30 water main leaks. It is not clear yet how bad the damage from the water main breaks has been. Locals have told CBS San Francisco in some neighborhoods the smell of gas persists.
Napa City Councilmember Peter Mott reports the library and the historic Chinese laundry building suffered significant damage, and bricks and glass are scattered across downtown sidewalks on Second and Third Streets. There are also reports of damage to numerous other buildings in the area.
At least two homes in Napa were still on fire after a mobile home park was set ablaze after the quake.
"There's collapses, fires," Napa Fire Capt. Doug Bridewell told the Associated Press. "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.
At least four homes in the mobile home park in Napa have burned down, and two more are believed to still be on fire.
San Francisco Chronicle reporter Will Kane reports firefighters struggled to control the blaze because of a water main break.
This was the largest quake to hit the Bay Area since the 6.9 magnitude quake hit Loma Prieta in 1989.
Leslie Gordon of the U.S. Geological Survey told the Associated Press the tremor struck at just before 3:30 a.m. Sunday. The epicenter was about six miles southwest of Napa, California, and about 50 miles west-southwest of Sacramento.
Jessica Turner of the U.S. Geological Survey told CBS San Francisco aftershocks of up to 5.0 are likely in the next week. There is only a 5 percent chance of a stronger quake during the next week. Already at least 25 aftershocks have rocked the region.
The USGS said the depth of the earthquake was just less than seven miles.
"A quake of that size in a populated area is of course widely felt throughout that region," Randy Baldwin, a geophysicist with the U.S. Geological Survey in Golden, Colorado, told the Associated Press. "The 6.0 is a sizeable quake for this area. It's a shallow quake."
Throughout the region, locals have reported the quake was felt as a long, rolling, shaking motion with several peaks of movement lasting for an extended time.
The California Highway Patrol reports some power outages.
The CHP is closing a bridge on Highway 37 in Vallejo while they inspect it for possible damage.
Widespread power outages are impacting Napa, and there are reports of minor damage across the region, mainly items falling off kitchen shelves and stores with broken bottles.
Callers to local radio stations and locals checking in on social media reported a significant shaking motion in the city of Napa, lasting for an extended time.
People as far away as the South Bay and Davis reported being woken up by the quake, which was centered 6.7 miles beneath Earth's surface.
Sonoma County also reported significant effects from the quake. The shaking was especially strong there because of the nature of the land being on alluvial gravel, sand and silt deposits, reports CBS San Francisco.
"Now that was a real earthquake," exclaimed San Francisco Sunset district resident Matt Wandell.
The White House said President Obama, who is returning from an often-interrupted two-week vacation today, has been briefed on the earthquake. A White House spokesperson said, "federal officials are in touch with state and local responders and the President will continue to receive updates."