PHOENIX (AP) - National forest crews have been dropping small combustible spheres from helicopters to help contain lightning-caused Snake Ridge Fire in Arizona.

The devices look like ping-pong balls and 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 the unsafe and remote area.

RELATED: Snake Ridge Fire crews expect smoke to blow away soon

Incident Commander trainee Jason McElfresh said the wildfire started May 19 roughly eight miles southwest of Happy Jack, Ariz. It has created smoky conditions but authorities expect to soon have the fire contained.