KANSAS CITY, Mo. (AP) — An employee who died during an explosion at an ammunition plant near Kansas City has been identified as a 55-year-old Missouri man.

The U.S. Army said Lawrence Bass, from Blue Springs, died Tuesday after the blast at the Lake City Ammunition Plant in Independence. The Army did not say how long Bass worked at the plant or in what capacity.

Four other employees were treated at the scene after the explosion in a building where chemicals are mixed.

The Bureau of Alcohol, Tobacco, Firearms and Explosives is leading the investigation.

The plant makes and tests small-caliber ammunition for the military. It also operates the NATO test center. The plant is operated by contractor Orbital ATK, the biggest maker of small-caliber ammunition for the U.S. Department of Defense.