'Fire on all sides': California wildfires prompt evacuations

More than 200 people were airlifted to safety overnight after a fast-moving wildfire cut off the only road out of the Mammoth Pool Reservoir in California's Sierra National Forest.

Twenty evacuees were taken to hospitals, the Madera County Sheriff's Department said on Twitter on Sunday, as the Creek Fire that started on Friday night rapidly grew to burn some 45,000 acres, forcing evacuations and road closures in the Fresno area in central California.

"We're completely trapped. There's fire on all sides, all around us," said Jeremy Remington, as he stood on a beach surrounded by fire in the Mammoth Pool Reservoir in a video posted on Twitter. Remington was later airlifted to safety, local news reported.

The blaze was 0 per cent contained on Sunday afternoon, while nearly 15,000 firefighters were battling some two dozen fires across the state, according to the California Department of Forestry and Fire Protection (CalFire).

Late on Sunday, California Governor Gavin Newsom declared a state of emergency in the Fresno, Madera, Mariposa, San Bernardino and San Diego counties due to the wildfires.

His office said that the declaration was prompted by the Creek Fire.

Eight people have been killed and some 3,300 structures have been destroyed over the past three weeks in wildfires across the state.

Three major fires, including the Creek Fire, were burning in Fresno, San Bernardino and San Diego counties, CalFire said in a statement, adding it had increased staffing in preparation for "critical fire weather".

The agency also said that the El Dorado Fire burning in the San Bernardino county was caused by a smoke generating pyrotechnic device, used during "a gender reveal party". The fire started on Saturday morning.

The San Diego County Sheriff's Department issued a voluntary evacuation order on Sunday afternoon as the 5,350-square acre Valley Fire raged unchecked on the eastern edge of the metropolitan area of more than 3 million people.

"The sky is so thick by my house; the sky is a dirty brown cloud and I live about 25 minutes to the west of the fire," Twitter user Cris Mel said in a post. "It’s kind of a struggle to breathe."

A dangerous heat wave was baking swaths of the western United States through the weekend, and many locations in California registered record-high temperatures on Sunday.