Watch: Thousands told to flee California floods and rainstorms

California has ordered the evacuation of thousands of homes after the US state was hit by rain and snow storms that left 17 people dead. A five-year-old boy remains missing after being swept away.

A fresh storm was set to pound the state with as much as 18 centimetres of new rain in northern California and several more metres of snow in the Sierra Nevada mountains, the National Weather Service said.

The occupants of two cars were rescued with minor injuries after their vehicles fell into a sinkhole that opened up on a Los Angeles road.