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

Authorities said that mass evacuations have taken place and at least 1,500 properties have been destroyed. Seven people were killed in Sonoma county.

Twenty thousands people fled from NAPA, Sonoma and Yuba counties after some of the state’s worst-ever wildfires broke out.

The governor of California has declared an emergency.

Along with the deaths in Sonoma county, two people were killed in NAPA county and one in Mendocino county when thousands of acres burned in one valley.

The head of California’s department of forestry and fire protection, Kim Pimlott, said that about one thousand five hundred buildings had already been destroyed.

Napa county’s Fire Chief warned that conditions were hindering firefighting efforts, as further resources were brought in from across the state.

The fires are particularly fast-spreading because of the combination of high winds, low humidity and hot, dry weather.

The national weather service has issued a warning for the san Francisco area that “Any fires that develop will likely spread rapidly”.