LAS VEGAS, N.M. — Schoolchildren in a northern New Mexico community that had been threatened by a wildfire resumed in-person classes Tuesday while residents on the fire’s northern and southern edges remained under evacuation orders.

The West Las Vegas School District said exceptions would be made for students still displaced by what’s the largest wildfire burning in the U.S. or those whose health has been affected by the smoke.

Still, classes for students in a neighboring school district that serves part of the community remained virtual while firefighters worked in rugged terrain ahead of the massive blaze trying to clear brush and stop the flames from burning more homes in the Rocky Mountain foothills.

The wildfire — intensified by decades of drought, warmer temperatures and spring winds — has burned more than 318 square miles (824 square kilometers) of tinder-dry ponderosa forests. Thousands of people have had to flee the flames and some 300 structures, including homes, have been destroyed.

Crews have spent days working to protect ranch homes scattered through the area and stamping out small fires that jumped ahead of the main blaze.

“So far they’ve had great luck in catching those,” said fire information officer Joel Barnett.

Wind and low humidity levels continued to be big wildfire expansion threats as the National Weather Service has issued red flag warnings for extreme fire danger in much of New Mexico and parts of Nevada, Arizona, Colorado and Texas. Forecasters said New Mexico is outpacing most other recent years for the number of red flag days in April and so far this month.

In northern New Mexico, officials at Los Alamos National Laboratory and residents in the nearby town are prepared to evacuate if a wildfire burning there moves closer. That fire has burned more than 66 square miles (171 square kilometers).

Officials said some medically fragile residents and large animals already have been moved out of the area to lessen the traffic congestion should evacuations be ordered. They anticipated residents would have at least a day or two notice if they need to flee.

“If the fire gets its fifth gear, it will be here sooner than we want it to be,” said incident commander Rich Harvey. “We’re doing everything we can to check it.”

Crews in Arizona were battling a fire near the U.S.-Mexico border that forced several dozen people from their homes.