UPDATE — 1:30 p.m. PT:
The U.S. Geological Survey has confirmed a 6.0-magnitude earthquake struck Northern California in the early hours of Sunday morning.
The earthquake took place about 6.6 miles below the surface about 6 miles from Napa, California, the USGS reported. Between 25 and 60 smaller aftershocks are expected in the area over the next week.
More than 42,000 customers lost power in the northern Bay Area, according to PG&E. Towns include American Canyon, Napa, Saint Helena, Santa Rosa, and Sonoma.
"It was a rolling quake," Oakland resident Rich Lieberman told the AP. "It started very much like a rolling sensation and just got progressively worse in terms of length. Not so much in terms of shaking, but it did shake. It felt like a side-to-side kind of rolling sensation. Nothing violent but extremely lengthy and extremely active."
More than 100 people were sent to the hospital with non-life threatening injuries, the Associated Press reported.
Most of the patients at the Queen of the Valley Medical Center in Napa had cuts, bumps and bruises, a spokesman said. Three people had broken bones, and two people had heard attacks. One child was in critical condition after being struck by part of a fireplace, the AP reported.
At least four homes were destroyed in a fire at a mobile home park, with a water main break making it difficult to put the fire out, Napa Fire Capt. Steve Becker told the San Francisco Chronicle.
Along with the minor injuries, ABC News is reporting two "major injury cases."
Images depicting the damage around Napa have appeared on social media.
Sunday's earthquake was the highest magnitude one in years. The Independent reports:
In 1989 an earthquake measuring 6.9 struck the Santa Cruz area of California, killing 62 people, according to government figures.
Prior to that one there had been quakes of 5.7 and 5.8 in 1983 and 1980 respectively.