Authorities in northwestern North Dakota are searching for explosives that belong to the U.S. Air Force.

Mountrail County Sheriff Ken Halverson says a belt of ammunition for an automatic grenade launcher was lost near Parshall. The explosives are contained in a green metal ammo can about 18 1/2 inches long, 14 1/2 inches high and 8 1/2 inches wide.

The ammunition was reported lost on May 4. Halvorson says a group of about 100 airmen walked the six-mile route several times on Friday and did not find the grenades.

Halvorson says the explosives are dangerous and specific to the Air Force launcher. He says the ammunition will not operate in any other device without "catastrophic failure."

Anyone with information about the explosives is asked to contact the Mountrail County Sheriff's Department.