The Lassen Volcanic National Park in Northern California has been forced to close as a massive wildfire continued to explode in size in the region.

The fast-moving fire, dubbed Dixie Fire, is active in the remote eastern side of Lassen Volcanic National Park, said park officials in a news release, noting that an emergency closure is in place for the entire park.

The Dixie Fire was at 322,502 acres and 35 percent contained as of Thursday morning, according to the California Department of Forestry and Fire Protection (Cal Fire).

“The temporary closure ensures firefighters have unimpeded access to all areas of the park,” said Jim Richardson, superintendent of the park.

“The park’s current priorities are to ensure the immediate evacuation of visitors and to protect facilities along the park highway and in the Manzanita Lake and Mineral Headquarters areas,” he added.

The fire, which started on July 13, has burned through multiple counties in Northern California.

It is the largest wildfire so far this year in California and became the sixth biggest in the history of the state after growing over 50,000 acres overnight.

Greenville, a small mountain town in the region, was devastated by the massive wildfire on Wednesday night.

The town, home to around 1,000 residents, is around 230 km northeast of the state capital, Sacramento.

Authorities in multiple Northern California counties on Thursday issued new mandatory evacuations and new warnings, urging residents in some communities near the fire zones to evacuate immediately.

Officials said over 12,400 structures were threatened by the fire and around 4,800 fire personnel were battling the blaze.

Extreme fire behavior with long-range spotting, crown fire, and group torching is anticipated, according to InciWeb, an inter-agency all-risk incident web information management system provided by the US Forest Service.

InciWeb added that initial reports indicate firefighting activities had saved about 25 per cent of structures in the Greenville community.

Over 6,000 wildfires have burned more than an estimated 579,600 acres and damaged or destroyed at least 400 structures in California so far this year, according to the Cal Fire’s 2021 Incident Archive.

The state and most of the US West Coast are in the grip of a severe drought of historic proportions.

Nationwide, 100 large fires have burned 1,947,811 acres in 14 states, the US National Interagency Fire Centre said Thursday.