VIDEO: CALIFORNIA MUDSLIDE KILLS 30 WITH HUNDREDS INJURED, TRAPPED OR MISSING

At least 30 people have died and hundreds injured and trapped after mudslides and flooding in southern California. Rescue workers are searching for survivors while 163 people have already been taken to the hospital. Twenty had "storm-related injuries" while four were critically hurt.

In some places mud was waist-deep, officials said, while the death toll is expected to rise.

More than 50 people have been rescued already but many places are still inaccessible with more than 30 miles (48km) of the main coastal roads closed, including the major Highway 101, police said the scene "looked like a World War One battlefield".

Rescuers said a group of 300 people are trapped in Romero Canyon, a neighbourhood east of Santa Barbara. Heavy rain run-off caused a mudflow in the community of Montecito, where some homes were knocked off their foundations, said Santa Barbara County Fire Department spokesman Mike Eliason.

The incident occurred after heatwave-ending rains caused mudslides when it drenched ground that had been exposed by December's huge wildfires.

"Recent burn areas will be especially vulnerable where dangerous mud and debris flows are possible," said the National Weather Service in a statement. The increased risk of flooding and mudslides occurs after a wildfire as the burned vegetation and charred soil create a water-repellent layer which blocks water absorption.

The Federal Emergency Management Agency (FEMA) says the risk of flooding stays "significantly higher" for up to five years after a wildfire.

Emergency services declared an exclusion zone, saying "anyone moving around the area would be in the way of rescuers and would be subject to arrest." This has forced thousands of people to leave their homes, with many of them having to evacuate for the second time in just two months.

Those who have stayed in the area have been warned to boil their tap water before drinking it.

County Fire Captain, Dave Zaniboni, said that five people were found dead on Tuesday in Montecito, possibly as a result of the storm.

The upmarket neighbourhood includes homes owned by celebrities such as actor Rob Lowe, chat show host Ellen DeGeneres and broadcaster Oprah Winfrey.

According to the BBC's Los Angeles correspondent James Cook, "Boulders the size of small cars were rolling down hillsides and blocking roads."

The US Coast Guard has sent "multiple airships to support rescue operations", warning the public to not fly drones which will cause rescue flights to be grounded.

California has suffered severe drought in five out of six of the past years.

In December, California Governor, Jerry Brown, said climate change meant wildfires could erupt "every year or every few years" and that the state was "facing a new reality".

2017 was the third warmest year on record, according to the US National Oceanic and Atmospheric Administration, setting a new record of $306bn (£226bn) spent on weather and climate-related disaster costs in the United States.

Check out the video below for more.