Wildfires rage in California, stoked by extreme heat in US West

Three large wildfires burned in California and a fourth was growing quickly on Monday as a weekend heat wave lingered across large swaths of the western United States.

The Creek Fire, which has engulfed the Fresno area in central California and caused the emergency evacuation over the weekend of more than 200 people vacationing at a popular reservoir, was still not contained as of Monday afternoon, fire officials said.

The blaze, growing under "extreme weather conditions," had devoured nearly 79,000 acres of land, while a cause remained under investigation, the California Department of Forestry and Fire Protection (CalFire) said in a statement.

Officials in Madera County issued evacuation orders and urged the county's 157,000 residents to leave if they felt unsafe.

The Oak Fire in Mendocino County started burning around 1:26 pm on Monday, according to CalFire, and three hours later it had already torched 1,000 acres and destroyed one structure.

Videos on social media showed the fire consuming pick-up trucks as it spread along Highway 101 near Willits, California.

San Francisco-based power provider PG&E said late on Monday that it began turning off power in "high fire-threat" areas. The outages will impact 172,000 customers in 22 counties, mostly in the Sierra Foothills, PG&E said, adding the shut off was a safety measure due to the extreme high and dry winds.

In Southern California, east of San Diego, more than 400 firefighters battled the Valley Fire, which burned more than 17,000 acres in Cleveland National Forest. Video shared on social media showed firefighters dousing the flames, the air thick with ash and fire embers.

The blaze was 3 per cent contained on Monday evening. Officials announced the deployment of military aircraft on Monday afternoon to help fight the flames.

A fire in San Bernardino County, southeast of Los Angeles, that officials said was caused by a pyrotechnic device used during a gender reveal party, kept burning through the night and was 7 per cent contained as of Monday morning.