An aerial view of the Cerro Pelado fire/Inciweb

With the continued growth of the Cerro Pelado wildfire in New Mexico, firefighters were to work Thursday on protecting structures at Bandelier National Monument and Valles Caldera National Preserve from the approaching flames that had reached the two parks' borders.

National Park Service staff at the two parks could not immediately be reached, but public information staff on the fire itself said crews would be involved with wrapping structures with fire resistant materials, installing sprinkler systems, and removing ground fuels and low-hanging limbs that could provide a "ladder" for flames to climb up into trees.

"The structure protection is going on in those parks," said John Nichols, part of the communications team on the Cerro Pelado fire. "They're wrapping those structures and doing hose lays and prepping to make sure that they're defensible. If they need to, they even burn out around structures like that, if necessary. So far, they didn't mention that that was being done. That's something that they usually hold off until they absolutely have to."

While a small portion of the fire had moved into the southeastern edge of Valles Caldera, fire bosses were concerned that if the main fire were to move north of New Mexico Highway 4 the flames would "rapidly spread in heavy grasses of the" preserve.

The fire started April 22 in the afternoon and quickly spread under gusting winds and dry fuels. As of Thursday morning it measured more than 29,000 acres. More than 750 firefighters, aided by aerial fire retardent drops, 10 bulldozers to create fire breaks, and nearly three dozen fire engines, had managed to get containment lines around 13 percent of the fire's perimeter. Helicopters equipped to start backfires were working in the northeast corner of the fire to "consume fuels to further secure the firelines."

However, gusting winds were said to be sending embers up to a half-mile ahead of the main fire. The weather forecast was not promising, either, as by Sunday an approaching front could generate "high winds and unstable conditions" that would "increase the potential fire behavior toward active and extreme," the daily fire report noted.