California's San Francisco Bay Area has been hit with a magnitude 6.0 earthquake Sunday morning.

The earthquake damaged several buildings and knocked out electricity to thousands of homes, according to ABC News. The real extent of the damage, however, was not immediately apparent, although there have been reports of hospitals being filled with victims needing treatment for injuries.

Napa Fire Dept. Capt. Doug Bridewell reported structural collapses and fires. "That's the worst shaking I've ever been in," he added.

The Bay Area was hit by the earthquake around 3:30 AM, about 10 miles away from the American Canyon, says Leslie Gordon of the U.S. Geological Survey. According to the USGS, this was the biggest quake to hit the area since the magnitude 6.9 Loma Prieta earthquake which happened in 1989.

Officials are reporting extensive power outages, but so far, no reports of major injuries have come in. Fox News says the quake managed to set off car alarms and wake up residents in neighboring Sonoma County.

"It was very jolting and probably went for 20 seconds . . . it was shaking pretty good," said Arik Housley, a resident of the area. Housley said he was awakened around 3:30 AM by the shaking, and also observed multiple fires in a mobile home park as he drove to his stores to evaluate the damage.

Napa residents also reported damages, and several counties had activated their fire departments along with the California Highway Patrol (CHP) to look for structural damage to bridges in the area, reports LA Times.

The CHP had already reported cracks along Route 121-Route 29. Highway 37 in Vallejo was also reported to have sustained several damaged areas in places where the concrete has crumbled, as well as some areas where the roadway has separated.

However, CHP Sgt. Eric Lund has said that the Carquinez and Benicia bridges have both been cleared and considered "damage free".