USS Iowa turret explosion
On 19 April 1989, an explosion occurred within the Number Two 16-inch gun turret of the United States Navy battleship USS Iowa (BB-61) during a fleet exercise in the Caribbean Sea near Puerto Rico. The explosion in the center gunroom killed 47 of the turret's crewmen and severely damaged the gun turret itself.
Source: Wikipedia — USS Iowa turret explosion (CC BY-SA 4.0)