At least 15 sailors were killed in an ammunition explosion and fire that ripped through the battleship USS Iowa Wednesday while on exercises 330 miles northeast of Puerto Rico, the Navy said.

The Iowa, a World War II battleship that was modernized and recommissioned in 1984, was participating in the Atlantic Fleet exercise "Fleetex 3-89" and firing its 16-inch guns during a routine gunnery exercise when an explosion tore through one of its gun turrets at about 8 a.m. MDT, the Navy said.At least 15 sailors were killed, he said, but the number of injuries to the 1,575 sailors aboard the ship and the extent of damage were not immediately available.

"The ship is not in danger of sinking," a Pentagon spokesman said. Vice Adm. Jerome Johnson, the 2nd Fleet commander, was aboard the Iowa but was unhurt.

The last U.S. warship to experience a gun turret explosion was the USS Mississippi when it was shelling Japanese-held Makin Island in the Pacific in November 1943. That explosion killed 43 sailors.

A Navy spokesman said powder bags are routinely packed behind the 16-inch guns and that an explosion would be extremely powerful.

The Iowa has nine 16-inch guns, 12 5-inch guns and is equipped with Tomahawk and Harpoon missiles.

The Iowa, one of four battleships that were modernized and brought back into service by the Reagan administration, sought medical assistance from the aircraft carrier USS Coral Sea, which was 133 miles west of the Iowa, the Navy said.

The Coral Sea was not expected to reach the Iowa until late Wednesday afternoon, a spokesman said.