Los Angeles, Feb. 7: A storm of historic proportions dumped a record amount of rain over parts of Los Angeles on Monday, sending mud and boulders down hillsides dotted with multimillion-dollar homes while people living in homeless encampments in many parts of the city scrambled for safety.

About 710,000 people state-wide were without power Monday evening.

The storm was the second one fuelled by an atmospheric river to hit the state over the span of days.

Virtually all of Southern California was under flash flood advisories and watches, including the Los Angeles area, where between 5 and 10 inches (12.7 to 25.4 centimetres) of rain had fallen and more was expected, according to the National Weather Service. At the downtown measuring station, 6.7 inches of rain had fallen by Monday afternoon, nearly half the yearly average of 14.25 inches. It was already the third-wettest two-day period since 1877, the service said.

So far officials have attributed three deaths to the storm that first hit Northern California. Crews rescued people from swift-moving water in various parts of Southern California on Monday, including 16 people and five cats in Los Angeles County alone, authorities said.

Also rescued were two homeless people who spent the night on a small island in the Santa Ana River in San Bernardino, about 55 miles (88.51 kilometres) east of Los Angeles, authorities said.

“They were cold and exhausted from a night out stranded on this little patch of dirt that was in the middle of the river,” said Capt. Nathan Lopez of the San Bernardino County Fire Department. A dog and two cats were also saved.

At a news conference, authorities said rain would taper off in intensity on Tuesday, but the threat of flooding remained high.

Near the Hollywood Hills, floodwaters carried mud, rocks and household objects downhill through Studio City, damaging at least two homes, city officials said. Sixteen people were evacuated.

The Los Angeles Fire Department said 1,000 fire-fighters were contending with 49 debris flows, 130 reports of flooding, half a dozen structure fires and several rescues of motorists stranded in vehicles.

Drake Livingston who lives in the Beverly Crest neighbourhood, was watching a movie around midnight when a friend alerted him to flooding.