Bulgarian officials say a U.S. citizen has been killed in a grenade-launcher accident and four other persons have been wounded.

Police said the accident occurred at noon Saturday at the firing range of an ordnance plant near the city of Sopot in central Bulgaria.

The Ministry of Economy said in a statement that one American was killed on the spot and another U.S. citizen was taken to a hospital with life-threatening injuries. A third American and two Bulgarians were also taken to a hospital with less severe injuries.

Names and hometowns were not immediately released.

The ministry said the accident occurred during "experimental shooting conducted by the All Guns private company." It said the ammunition used was manufactured in Bulgaria in 1984.