An explosion May 5 at the U.S. Army’s Redstone Arsenal in Huntsville, Ala., killed two contractors working with a key ingredient of solid-rocket propellant.

The Army said in a May 6 press release that the two men, both employees of Huntsville-based AMTEC Corp., were working on “demilitarization operations” that involved ammonium perchlorate, an oxidizer in solid-rocket propellant used in missiles and booster rockets.

The explosion occurred at a facility operated by the Army’s Aviation and Missile Research, Development and Engineering Center. The injured men, whose names were not released by the Army or their employer, were taken to the University of Alabama at Birmingham Hospital, where they died.

The Army said in a May 6 press release that the building had recently passed safety inspections and was designed specifically to minimize the impact of possible explosions.

AMTEC provides test and evaluation support, systems engineering, manufacturing and fabrication services for the Department of Defense, NASA and commercial clients.