RESERVE, N.M. — A wildfire burning in what New Mexico’s governor called “impossible” terrain in an isolated, mountainous area of the state continued its rapid growth today as forecasters called for thunderstorms and dry lightning that could spark even more fires.

The massive blaze in the Gila National Forest in southwestern New Mexico is the biggest in state history and the largest currently burning in the country. It scorched an additional 39 square miles in the past day, growing to nearly 340 square miles, as more than 1,200 firefighters worked to halt its spread.

Additional Photos

Firefighters work an area along the northwest perimeter of a massive blaze in the Gila National Forest in an isolated mountainous area of southwestern New Mexico. AP

Firefighters are creating more burnout operations to battle the erratic blaze that has injured six people, the fire’s incident management team said today. Details on the injuries were not immediately available.

Officials said the fire is around 10 percent contained.

Though crews are being helped with increased humidity levels, forecasters say there’s a chance for thunderstorms and dry lightning over New Mexico’s Black Hills area that could spark more fires.

Gov. Susana Martinez viewed the fire from a New Mexico National Guard helicopter Thursday and saw the thick smoke shrouding some of the steep canyons that are inaccessible to firefighters. She described the terrain as “impossible,” saying there was no way for firefighters to directly attack the flames in the rugged areas of wilderness.

“It’s going to keep going up,” she said of the acreage burned. “Be prepared for that.”

Along the fire’s northern edge, Martinez spotted crews doing burnout operations designed to slow the erratic blaze, which has surpassed last year’s Las Conchas fire as the largest ever in recorded state history. That fire charred 156,593 acres and threatened the Los Alamos National Laboratory, the nation’s premier nuclear facility.

From the air, Martinez could see the blanket of smoke stretching for miles. She used words like “daunting” and “enormous,” fitting since fire managers said the blaze could smolder until the region gets significant rainfall during the summer monsoon season.

So far, the fire has destroyed a dozen cabins and eight outbuildings, fire information officer Iris Estes said.

Officials closed the Gila Cliff Dwellings National Monument on Thursday due to smoke generated from the fire. The National Park Service said the closure will remain in effect until conditions improve.

The wildfire near the Arizona border is fueling experts’ predictions that this is a preview of things to come across the West as several states contend with a dangerous mix of wind, low humidity and tinder-dry fuels.

Related Stories