A California storm on Christmas Eve caused flooding and mudslides, and prompted evacuations, power outages, and travel warnings as heavy rains hit the region.

A strong atmospheric river is moving across Southern California, bring heavy rain and threatening mudslides in recent burn scar areas.

Heavy rain storms across large parts of California triggered floods and mudslides and left three dead as of Christmas night, according to local officials. The storms - which were expected to continue through Friday - brought 11 inches (27 cms) of rainfall to some parts of Los Angeles County, prompted evacuations and shut down major roads.

The National Weather Service says snow and high winds are expected, while heavy rain could pose possibly 'life-threatening' risks in parts of the region.

A Severe Thunderstorm Warning has been issued for east central Ventura County and northwestern Los Angeles County until 8:30 a.m.

More than 41 million Americans across California, Nevada and Arizona are under flood watches on Wednesday amid a rare, high risk for excessive rainfall and flooding.

Rain totals will range from about 2 to 4 inches over the 3-day stretch from Wednesday to Friday with the heaviest accumulations in North County.