At least two people have been injured and tens of thousands of homes and businesses left without power after a strong earthquake hit northern California.

The “insane” 6.4-magnitude quake struck on Tuesday at 2.34am local time (10.34am UK time), with its epicentre just off the coast and about 10 miles (16.km) deep, but there was no tsunami threat.

Residents reported there was shaking for up to 20 seconds.

The quake happened near to the town of Ferndale in Humboldt County.

More than a dozen smaller quakes appeared to hit parts of the region afterwards, the US Geological Survey said.

The main earthquake caused widespread damage to roads and homes, along with a bridge, while power lines were brought down and there were numerous gas leaks.

Ferndale, where the two injuries took place, is home to about 1,400 people and located 261 miles (420km) north of San Francisco.

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One person broke their hip and another suffered a head wound, said the sheriff’s office.

More than 72,000 homes and businesses were without power there and elsewhere in the county, according to tracking website Poweroutageus.com.

And the California highway patrol was responding to reports of cracks in the Ferndale bridge over the Eel River in and out of Ferndale.

‘That was big’

Caroline Titus, a Ferndale resident, tweeted a video in her darkened home of toppled furniture and smashed dishes.

“Our home is a 140-year-old Victorian. The north-south shaking is very evident in what fell,” she tweeted.

“That was a big one,” she said in another message.

Another Twitter user Jimmy Eller, who said he lived in Humboldt County, wrote: “That earthquake was insane. A good 15-20 seconds of shaking.”

And the sheriff’s office tweeted: “Due to a large earthquake, widespread damages to roads and homes are reported throughout Humboldt County.

“Be prepared for aftershocks. Check gas and water lines for damages or leaks. Exercise caution if travelling.”