On 19 April 1989, the Number Two 16-inch gun turret of the United States Navy battleship USS Iowa (BB-61) exploded. The explosion in the center gun room killed 47 of the turret's crewmen and severely damaged the gun turret itself. Two major investigations were undertaken into the cause of the explosion, one by the U.S. Navy and then one by the Government Accountability Office (GAO) and Sandia National Laboratories.