Quake shakes northern California
An earthquake with a preliminary magnitude of 6.0 has been reported in California's northern San Francisco Bay area, officials said.
The tremor struck at just before 3.30am local time about 10 miles north west of American Canyon, which is about six miles south west of Napa, said Leslie Gordon, of the US Geological Survey (USGS).
It is the largest tremor to shake the Bay Area since the 1989 6.9 magnitude Loma Prieta quake, the USGS said.
The tremor set off car alarms and had residents of neighbouring Sonoma County running out of their houses in the middle of night. Power was knocked out in some areas.
The depth of the earthquake was just under seven miles, and numerous small aftershocks have occurred in the Napa wine country, the USGS said.
A member of Napa County dispatch told the Associated Press that there has been one report of structural damage, but additional details were not available.
There was no immediate report of injuries.
Oakland resident Rich Lieberman described the earthquake as a "rolling quake".
He said: "It felt like a side-to-side kind of rolling sensation. Nothing violent but extremely lengthy and extremely active."