Two fast-moving wildfires in California are threatening homes and could result in the evacuation of hundreds of people, US officials say.

In the Sacramento region, a fire has spread to cover an area of about 4,000 acres, while another blaze threatens homes around Yosemite National Park.

The Sacramento fire is only 20% contained, officials told local media.

Months of drought have caused more fires in California this year – some 1,400, twice the usual number.

The Sacramento fire in the north of the state has doubled in size since it broke out on Friday afternoon, the Los Angeles Times reported officials as saying.