Sharjah24 - AFP: A fierce California wildfire expanded Sunday, burning several thousand acres and forcing evacuations as tens of millions of Americans sweltered through scorching heat.

More than 2,000 firefighters backed by 17 helicopters have been deployed against the Oak Fire, which broke out Friday near Yosemite National Park, the California Department of Forestry and Fire Protection (CAL FIRE) said in a report.

But two days after it began, the blaze has already consumed more than 14,200 acres (5,750 hectares) and remains zero percent contained, the report said, adding that heat combined with low humidity would "hamper" efforts Sunday.

"Extreme drought conditions have lead to critical fuel moisture levels," according to CAL FIRE's report.

Described as "explosive" by officials, the blaze has left ashes, gutted vehicles and twisted remains of properties in its wake, as emergency personnel worked to evacuate residents and protect structures in its path.

It has already destroyed 10 properties and damaged five others, with thousands more threatened.

More than 6,000 people had been evacuated, said Hector Vasquez, a CAL FIRE official.

"It was scary when we left because we were getting ashes on us, but we had such a visual of this billowing. It just seemed like it was above our house and coming our way really quickly," one woman who had to be evacuated, Lynda Reynolds-Brown, told local news station KCRA.

"We started getting our stuff together, and that's when I went back up the hill and looked and I'm like, 'Oh my God.' It was coming fast," her husband Aubrey Brown told the station.

California Governor Gavin Newsom on Saturday declared a state of emergency in Mariposa County, citing "conditions of extreme peril to the safety of persons and property."

In recent years, California and other parts of the western United States have been ravaged by huge and fast-moving wildfires, driven by years of drought and a warming climate.