Crews drop exploding balls to help contain Arizona wildfire

Posted: Updated:
National forest crews have been fighting fire with fire in the last week by dropping combustible spheres that resemble ping pong balls. (Source: Coconino National Forest) National forest crews have been fighting fire with fire in the last week by dropping combustible spheres that resemble ping pong balls. (Source: Coconino National Forest)
PHOENIX (AP) -

National forest crews have been fighting fire with fire in the last week by dropping combustible spheres that resemble ping-pong balls from helicopters to help control a lightning-caused blaze in Arizona.

The devices are filled with flammable substances that cause them to ignite once they hit the ground. By using the exploding balls, authorities didn't have to send firefighters into unsafe and remote areas.

"The flammable spheres burn out in a circular pattern on the forest floor, as each circle of fire slowly grows they eventually burn into each other," said Kaitlyn Webb, a spokesperson for Coconino National Forest.

[ORIGINAL STORY: Lightning-caused wildfire above Mogollon Rim helping to clean forest]

[SPECIAL SECTION: Arizona wildfires]

The fire started on May 19 roughly 8 miles southwest of Happy Jack, Arizona, and has since covered more than 12.5 square miles, Incident Commander trainee Jason McElfresh said.

McElfresh said the exploding devices are among a variety of tools that crews use to combat wildfires. Along with aerial ignition, crews often use hand ignition as a key tool, he said.

[READ MORE: Closure order in effect after lighting-caused wildfire within Coconino National Forest]

"Crews walk around with what we call drip torches, which have a fuel mixture inside and they drip fuel onto a wick, which in turn drips fuel when it's lit onto the ground and makes a path of fire," McElfresh said.

The majority of the forest hasn't seen a fire in 20 to 30 years, Webb said, but like other ponderosa pine forests, it should be experiencing a fire every five to 12 years as part of a natural cycle.

[RELATED: Firefighters continue to monitor Snake Ridge Fire]

The area usually has four patrol units, but it had up to 11 over Memorial Day weekend, Webb said. Some units were posted in different sections of the fire closure area while others monitored the effect of smoke on the highway during the night to make sure people could continue to drive.

"Waiting on winds is going to be the name of the game on this one," Webb said. "It's all weather dependent, but if we get good winds, then we hope to have it contained early next week."

Click/tap here to download the free azfamily mobile app.

© 2017 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.