Fuelled by extreme heat, dry forests and underbrush, the Oak Fire that began on Friday has spread rapidly in California forcing thousands of evacuations in the nearby area, with more than 400 firefighters battling the blaze

Governor of California Gavin Newsom declared a state of emergency for Mariposa County on Saturday due to the effects of the Oak Fire. He said the state has secured a grant from the Federal Emergency Management Agency to help ensure the availability of vital resources to suppress the fire.

Firefighters have deployed air tankers, bulldozers and hand crews to battle a fast-moving wildfire just west of Yosemite National Park on Sunday that suddenly and unpredictably grew into what has become one of the largest fires of the year.

The Oak Fire that closed within half a mile (0.8 km) from the town of Mariposa Pines, 10 miles (16 km) from Yosemite. By Sunday evening, the fire had consumed 15,603 acres (6,314 hectares) and was zero percent contained, according to the latest update from California Department of Forestry and Fire Protection (Cal Fire).

Around 3,800 people were under evacuation orders, Mariposa County Sheriff Jeremy Briese told a public briefing at a crowded auditorium in the town of Mariposa, the county seat. Cal Fire officials said they had robust firefighting teams on scene early on, but the fire progressed atypically and overran their best efforts.

The fire was moving east up into the sierra, toward the town of Mariposa Pines and in the direction of Yosemite, Justin Macomb, a Cal Fire operations section chief, told the public meeting.

“The fire quickly outflanked us. We couldn’t even attack it with the resources that we had on hand,” Macomb said. “In my career, I haven’t seen fire behaviour like that.”

Daniel Patterson, a spokesman for the Sierra National Forest, said that climate change has made the region much warmer and drier over the past 30 years which has led to California experiencing increasingly large and deadly wildfires.

Patterson said: “The fire is moving quickly. This fire was throwing embers out in front of itself for up to two miles yesterday. These are exceptional fire conditions.”

The cause of the fire remains under investigation.