Rescue efforts are underway as California struggles with flooding and landslides

California officials are conducting rescue efforts after an avalanche caused landslides and flooding in California.

The actions come a day after Los Angeles recorded its wettest day on record. On Monday, the mayor declared a state of emergency.

About six months worth of rain was expected to fall in and around Los Angeles in 24 hours on Monday.

“Atmospheric rivers” that cause storms have already brought rain, wind and snow to California.

The storm was linked to the death of one person after a tree fell in the Sacramento Valley on Sunday due to strong winds. Another person died after a tree fell on a home in Santa Cruz County.

Officials have issued evacuation orders for some hilly areas in Southern California, including Los Angeles and Santa Barbara.

“It's more important now than ever to stay safe and stay off the roads,” L.A. Mayor Karen Bass said Monday as she declared the state of emergency.

“Leave your home only if absolutely necessary.”

Emergency has also been declared by the Governor in eight districts of the state.

Landslides and debris flows were reported. On Sunday, 16 residents were evacuated from their Hollywood Hills homes.

Witnesses reported seeing refrigerators and pianos running through the streets amid the rubble.

Damage was also reported in LA's upmarket Bel Air and Beverly Hills neighborhoods.

“It sounded like lightning,” Beverly Glen resident Dave Christensen told KTLA-TV.

“When I went out to see what was there, I saw there was a water heater where the house had been, and it must have been enough, because the house slid down the hill and onto the road.”

Rescue crews had to help stranded drivers in Los Angeles and San Bernardino County.

A father, mother and daughter were ejected from their car early Monday morning and managed to climb a tree to escape rising flood waters, according to San Bernardino County Fire.

Beach fire rescue crews helped 19 boaters stranded on rocks near the Long Beach breakwater after a 50-foot (15-meter) sailboat lost its mast in strong winds.

Lifeguards sent rescue swimmers to make contact with the crew, who then assisted them to one-man rescue boats with life-threatening injuries.

Wind gusts of up to 70mph (112km/h) caused power outages and downed trees, although winds are forecast to ease significantly by Monday night.

It follows what was already a record-breaking day in the state. The National Weather Service (NWS) reported that 4.1in (10.4 cm) of rain fell on downtown Los Angeles on Sunday, breaking the previous record of 2.5in set in 1927.

Nearly half a million people were without power Monday morning after the storm knocked out power.

The storm also forced the closure of schools in Malibu, as some employees were unable to get there due to flooded and closed roads. Schools were also closed further north in Sonoma County and the city of San Jose, near San Francisco.

Police in Los Angeles say debris flows and landslides have damaged many homes and vehicles, and there has been a sharp increase in traffic accidents.

San Francisco has seen landslides in and around the city.

“Very heavy” snow will continue in the Sierra Nevada mountains, the NWS said, making travel “dangerous and impossible.”

The storm is due to an “atmospheric river” effect, caused by airborne currents of dense moisture.

Atmospheric rivers are a phenomenon in which water evaporates into the air and is carried by the wind, creating long currents that flow in the sky like rivers on land.

The first atmospheric river hit California last week. An updated bot of bad weather is caused by a second.

In a statement declaring a state of emergency in eight counties, including Los Angeles and Orange, Governor Gavin Newsom said: “This is a serious storm with dangerous and life-threatening implications.

“California is prepared with registered emergency assets on the ground to respond to the impacts of this storm.”

Two other districts have declared their own states of emergency.