In this file photo taken on Aug 24, 2014, bricks and rubble cover the sidewalk in front of a heavily damaged building following an earthquake in Napa, Calif. (ERIC RISBERG / AP)
A strong 6.4-magnitude earthquake that struck off the coast of northern California on Tuesday rocked people awake, damaged a bridge, caused gas leaks and left thousands without power.
The earthquake struck at 2:34 a.m. local time (1034 GMT) and was about 10 miles (16.1 km) deep, the US Geological Survey (USGS) said. It struck about 7.4 (12 km) west-southwest of Ferndale, California, a Humboldt County town that is home to about 15,000 people and located 261 miles (420 km) north of San Francisco and just south of Eureka.
Local media and others on social media reported numerous gas leaks, downed powerlines and at least one structure fire in Ferndale
Local media and others on social media reported numerous gas leaks, downed powerlines and at least one structure fire in Ferndale. A representative from the Humboldt Sheriff's Office was not immediately available for comment.
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It is unclear if the earthquake caused any serious injuries or deaths.
Local media reported that the California highway patrol was responding to reports of cracks in the Ferndale bridge over the Eel River in and out of Ferndale.
Highway 101 and Highway 299 remained open through Humboldt County, State Senator Mike McGuire said on Twitter, noting that transportation officials were assessing state highway infrastructure.
"That earthquake was insane," said Twitter user Jimmy Eller, who said he lived in Humboldt County. "A good 15-20 seconds of shaking."
The earthquake caused strong shaking and likely produced light to moderate damage, according to the USGS, which uses a seismometer to measure the time, location and magnitude of a tremor. An earthquake's intensity depends on its distance from a fault, its direction and the local geology.
About five earthquakes of magnitudes between 6.0 and 7.0 happened each year in California and Nevada, according to recent data, the Los Angeles Times reported.
More than 3,500 people reported to the USGS that they felt the earthquake and the more than a dozen aftershocks reported in the aftermath, the service said online.
READ MORE: Injuries, damage reported after powerful quake hits California
Caroline Titus, the editor and publisher of The Ferndale Enterprise, posted video on Twitter of toppled furniture and household items scattered on the floor.
"Sorry for dark video. Power still out," Titus tweeted from Ferndale.
More than 72,000 homes and businesses were without power in Ferndale and surrounding Humboldt County, according to the electric grid tracking website Poweroutageus.com.
The California Independent System Operator, which oversees much of the state's electrical grid, issued a transmission emergency notice for the area following the earthquake.
There was no risk of a tsunami, the US tsunami warning system said.