EGLIN AFB — Firefighters were continuing late Friday afternoon to battle two wildfires that began Thursday on the base's test ranges in Santa Rosa County and had consumed a total of 2,400 acres as of the last report from Eglin's Wildland Support Branch.

According to the update, delivered late Friday morning, the fire that began on Test Area A-77 west of State Road 87 and north of Holley "is currently at 1,900 acres and is approximately 35 percent contained at this time."

Because Test Area A-77 is a UXO location — a test range where unexploded ordnance is in the ground — firefighters can't attack the blaze directly, but must construct fire lines — areas cleared of vegetation and other fire fuels — to contain it. Friday's plan for fighting that fire, according to the morning update, included "improving existing lines and scouting for opportunities to continue to construct fire lines."

It was also possible, according to the update, that firefighters could "conduct a burnout operation that would increase the fire to around 4,000 acres but would make containment and control much easier and quicker." In a burnout operation, a fire is deliberately set within a controlled area to consume fuel as the original fire advances.

"If it is determined a burnout is necessary, there may be temporary smoke impacts to coastal areas along Highway 98 in the Florosa/Hurlburt Field area," according to the update.

A smoky haze wafted across the highway Friday, but it was not immediately clear whether that smoke was from a burnout operation. No update on the fire was available from the Wildland Support Branch as of early Friday evening.

According to Eglin Air Force Base spokesman Mike Spaits, no clear cause has been established for the fire, although there is some speculation that it may be connected with activities of the Hurlburt Field-based Air Force Special Operations Command.

The Test Area A-77 fire, now called the "Wet Pond Fire," is being managed by Eglin's Wildland Support along with the Florida Forest Service, the U.S. Fish and Wildlife Service, the Bureau of Land Management and the Longleaf Alliance, which coordinates management and restoration of longleaf pine forests.

The second fire in Test Area A-78, a UXO location northeast of Holley, had consumed 500 acres as of late Friday morning and was 10 percent contained, according to the Wildland Support Branch. According to Spaits, that fire began during a training mission of the Army 7th Special Forces Group (Airborne). As with the Wet Pond Fire, work on the Test Area A-78 fire Friday was slated to "include improving dozer lines and continued scouting for additional opportunities to construct fire lines."

Also as with the Wet Pond Fire, the Test Area A-78 fire "is being managed by members of the Eglin Wildland Support Module with assistance from Florida Forest Service, U.S. Fish & Wildlife Service, Bureau of Land Management and Longleaf Alliance," according to the 11 a.m. Friday update on the blazes.

A Friday morning reconnaissance flight over that area was designed to "give better mapping and acreage and will provide additional information to ... make operational decisions," according to the statement.