Federal authorities have offered a $10,000 reward for help solving three explosions involving homemade flashlight bombs that injured five people.

Investigators with the Phoenix field office of the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) are now investigating the case with the FBI, Phoenix Police Department, and Glendale Police Department. The ATF has provided local law enforcement bomb squads with "render safe" procedures, Special Agent Tom Mangan told POLICE Magazine.

In May, three improvised explosive devices contained within yellow, plastic 6-volt flashlights exploded, after victims found the items and tried the on-off switches to determine if the flashlights worked.

Physical evidence shows the post-blast debris is consistent in each of the three explosions, Mangan said.

"The majority of IEDs that come into contact with law enforcement involve juveniles who are experimenting with powders or homemade explosives," Mangan said. "Those devices are crude. This device shows a level of sophistication."

The first explosion occured in Glendale on May 13. The flashlight was discovered in the landscaping area of a business. Two people were injured when the flashlight exploded.

On May 14, a flashlight was found in the landscaping area of a second business. One person was injured by the explosion.

And on May 24, the third flashlight bomb was found by an employee of a Salvation Army Rehabilitation facility. Two people who found the flashlight in donated goods were injured by the explosion.

"Our immediate concern is that of public safety. If anyone discovers a flashlight that does not belong to them or appears out of place, no matter the color or shape, do not attempt to touch or maniplate the flashlight in any way," said Thomas Atteberry, the ATF's special agent in charge in Phoenix.

Related:

The Hazards of Homemade Explosives