Coastal communities braced for mudslides as precipitation from what meteorologists call an "atmospheric river" bore down on roads and hillsides.

Footage from California's Highway Patrol shows massive boulders crashing down on a roadway.

A sinkhole in Los Angeles swallowed up vehicles.

Commuters sloshed through tunnels in LA's Union Station.

The state has been hit with series of storms in recent weeks with more forecast to come.

Barry Parker is the Ventura County Fire Division chief of operations.

"This storm was different from the standpoint that it was here much longer. It was more intense because of the prior storm, the ground was much more saturated, which led to a lot more flooding and a lot more rescues because of the ground saturation."

A National Weather Service meteorologist said six atmospheric rivers have hit California in the past 17 days, dumping as much as 30 inches of rain in some areas.

California Governor Gavin Newsom said the storms have killed at least 17 people in just 11 days.

The wealthy mountain enclave of Montecito was under a mandatory evacuation order earlier this week as flood warnings escalated.

Residents now cleaning up debris said fleeing wasn't so simple.

"The rain. The heavy, heavy downpour that started happening. They, they encouraged everybody to get out of Montecito. But there were - when it started happening, it was gridlocked."

Local media on Tuesday reported a Ventura County sheriff's helicopter rescued half a dozen residents who were left stranded near Ojai after mudslides cut off the only road through Matilija Canyon.

Experts say the growing frequency and intensity of such storms are symptoms of climate change. Combined with increasing drought and wildfires - both fueled by a warming planet - leave hillside communities vulnerable to devastating floods.

Aaron Ready and his family live in La Conchita, near Santa Barbara. His wife and children evacuated to a hotel, while he stayed behind and eyed bluffs looming over his home.

"Here. We're not necessarily impacted by flooding, but we are impacted by the hillside behind us. And so we keep an eye on rain totals where, and then that thankfully, we still have electricity, we still have utilities to shelter in place."

The high winds wreaked havoc on the power grid. Data from Poweroutage.us showed 51,000 homes and businesses without power as of early Wednesday.