Parts of California's wine region are being ravaged by fast-spreading fires that have killed at least 10 people.

A state of emergency was declared in northern areas after mass evacuations, with 1,500 properties destroyed.

About 20,000 people fled from Napa, Sonoma and Yuba counties in response to some the state's worst-ever wildfires.

Such fires are more common in southern California but a combination of dry weather and strong winds has fuelled the destruction in the north.