A large earthquake rolled through California's northern Bay Area early Sunday, damaging some buildings, knocking out power to thousands and sending residents running out of their homes in the darkness. The extent of the damage wasn't immediately clear.Napa Division Fire Chief John Callanan said, two major injuries have been reported, and hospitals have been very busy with moderate injuries. Leslie Gordon of the U.S. Geological Survey said, the 6.0 magnitude earthquake struck just before 3:30 a.m. about 10 miles northwest of American Canyon, which is about 6 miles southwest of Napa, in California wine country.