The strongest quake to hit California in a quarter century saw scores of people hospitalized, caused houses to burst into flames, and damaged scores of buildings in California's Napa Valley.
A 6.oh magnitude earthquake rocked California's wine country at around 3:20am on Sunday, local time, with the epicenter less than 10 kilometers southwest of Napa.
The earthquake was felt over a huge portion of California, in San Francisco, but the most powerful tremors were recorded in Napa and Sonoma County.
More than 30 aftershocks followed the quake, according to the U.S. Geological Survey.
Officials at Queen of the Valley Medical Center in Napa say at least six people have been critically injured with 120 less seriously hurt.
California Governor Jerry Brown has declared a state of emergency, and said state officials were working closely with state and local emergency managers, first responders and transportation officials.
California is not a safezone when it come to earthquakes, as it sits right above the Pacific's "Ring of Fire," where earthquakes and volcanic eruptions occur often.
In 1906, San Francisco was struck by 7.8 magnitude quake that killed over 3-thousand people and destroyed 80-percent of the city.
In 1989, another powerful quake hit in a similar area, killing more than 60 and injuring hundreds.
Shin Se-min, Arirang News.