Napa Fire Department Operations Chief John Callanan says the city has exhausted its own resources extinguishing six fires, transporting injured residents, searching homes for anyone who might be trapped and answering calls about gas leaks, water main breaks and downed power lines. The governor issued a proclamation directing state agencies to respond with equipment and personnel.
Leslie Gordon of the U.S. Geological Survey said the tremor, dubbed the South Napa earthquake, struck just before 3:30 a.m. Sunday about 10 miles northwest of American Canyon, which is about 6 miles southwest of Napa. The USGS said it was the largest tremor to shake the Bay Area since the 1989 6.9 magnitude Loma Prieta quake.
VIDEO: Families assess major damage in Napa neighborhood
More than 200 people were treated for earthquake-related injuries at Queen of the Valley Medical Center in Napa, and about a dozen were admitted, the hospital said in a statement. Most patients suffered minor lacerations and abrasions and were treated in the emergency department and released. Three were admitted with broken bones and two for heart attacks.
One person remained in critical condition Sunday night. A 13-year-old boy was also listed in serious condition. He was flown to the UC Davis Medical Center for a neurological evaluation after being struck by part of a fireplace, John Callanan of the Napa Valley Fire Department said.
"While it appears we have treated all patients injured during the earthquake, we are now seeing patients come to the hospital with injuries sustained during clean up. We want to urge the community to use caution when cleaning debris," the hospital said in a statement. "Please be careful as we don't want community members sustaining injuries unnecessarily. Please stay safe as we put our homes and businesses back together."
VIDEO: South Napa earthquake aftermath: Dozens injured, homes destroyed, thousands without power.
The tremor set off car alarms and had residents of neighboring Sonoma County running out of their houses in the middle of the night. Gas line ruptures from the quake caused six significant fires and destroyed four mobile homes on Orchard Avenue, Napa Division Fire Chief Darren Drake said. Firefighting efforts were complicated by broken water mains. Crews responded to at least 50 gas main breaks and 30 water main leaks, the city of Napa reported.
Officials in Napa said 90 to 100 homes have been deemed uninhabitable. Napa City Manager Mike Parness said 14 to 15 buildings were red-tagged. Several historic buildings were also damaged, including Sam Kee Laundry, Goodman Library and the Napa County Courthouse.
VIDEO: Thousands of dollars in wine lost in quake
Several people living in the region reported falling dishes and violent shaking inside their homes. Widespread power outages were also reported in Napa, Sonoma and Santa Rosa counties. More than 5,000 people remained without power Sunday night.
Highway Patrol and the California Department of Transportation were evaluating damaged buildings, bridges and roads. Amtrak suspended its train service through the Bay Area so tracks could be inspected.
A Red Cross evacuation center has been set up in the Napa High School gym. All Napa Valley Unified School District campus will be closed on Monday, officials said.
PHOTOS: Click here to see images of some of the damage.
The depth of the earthquake was just less than 7 miles, the USGS said. The USGS reported 86 aftershocks followed the quake, including a 3.6-magnitude aftershock which struck near the Napa wine county around 5:47 a.m.
Approximately 30 to 70 small aftershocks are expected in the next seven days, the USGS said. In addition, the possibility of a strong and possibly damaging aftershock in the next seven days is approximately 54 percent.
U.S. Sen. Barbara Boxer (D-California) sent her thoughts to earthquake victims and discussed her plan to help with recovery efforts.
"My thoughts are with all those injured and displaced by this powerful earthquake that caused significant damage in Napa and other communities," she said in a statement. "I am sending my field staff to Napa tomorrow and I will be talking to local officials about how we can help ensure that residents, businesses and communities have the resources they need to recover and rebuild."
President Barack Obama was briefed on the earthquake Sunday morning, a White House spokesman said.
Quake caught on camera
The Associated Press contributed to this report.