Federal authorities are offering a $10,000 reward for information on how a stockpile of stolen military explosives came to be buried in a rural area in central Arizona. Authorities say the explosives have been in the ground for about 20 years.

The Bureau of Alcohol, Tobacco, Firearms and Explosives says a construction crew clearing land near Pine unearthed the explosives in October.

Authorities say 80 blocks of C4 plastic explosives, nine claymore antipersonnel mines and a roll of detonating cord were found about 5 feet underground inside large plastic pipes. Authorities did not say where the explosives were stolen.

The ATF is offering the reward for information that leads to an arrest and conviction of anyone responsible for the theft.