WASHINGTON -- The Navy launched an investigation into the explosion and fire aboard the World War II battleship USS Iowa as the final casualty toll was placed Thursday at 47 dead and 10 to 12 crewmen slightly injured.
At the same time, a former commanding officer of the Iowa said early reports from the ship suggest that 660 pounds of black powder in the top of the ship's gun turret exploded for some unknown reason.
The Iowa, modernized and recommissioned in 1984, was firing its huge 16-inch guns during routine gunnery practice about 200 miles northeast of Puerto Rico Wednesday when an explosion ripped through gun turret No. 2 on the front of the ship.
The Iowa was one of 29 U.S. Navy ships taking part in the Atlantic Fleet training exercise 'Fleetex 3-89.'
'Forty-seven crewmen are dead. Between 10 and 12 have suffered minor injuries, most of these were in the firefighting party. There are no serious injuries,' Pentagon spokesman Fred Hoffman said.
The bodies of the dead were to be flown from Puerto Rico, where the Iowa was due to dock, to Dover Air Force Base in Delaware Thursday afternoon. The Iowa then planned to return to its home port of Norfolk, Va.
A special Navy board chaired by Rear Adm. Richard Milligan, a former commanding officer of the Iowa's sister ship, the USS New Jersey, was named to investigate the cause of the accident and to report its finding later.
Hoffman said the damage 'seems confined to the turret. It is not affecting the ship in any other way. The extent of the damage to the turret is really unknown at this time.'
Hoffman said the gun turret was fully manned with 74 men at the time of the accident.
Navy Capt. Larry Seaquist, who commanded the Iowa until last May, said the turret is 'equivalent to a seven-story high building. This turret No. 2 weighs about 1,800 tons ... about what a World War II destroyer weighs.'
'The early reports were that the explosion was up in that gun room' -- the top level of the gun turret, Seaquist said.
To fire the huge 16-inch guns, projectiles are moved by machinery up from the bottom levels of the turret to the gun room and placed in barrels. Then 660 pounds of black powder are moved from the lowest level of the turret to the gun room to be packed in behind the projectile for firing.
'It seems from the reports that those powders exploded,' Seaquist said. 'Those powders are designed to produce massive amounts of gas' to propel the 2,300-pound projectiles at a speed of 1,500 mph.
'We simply do not know what caused that powder' to explode, he said.
'This gun, the mark-7 16-inch 50-gun, remains the finest naval gun in the world,' Seaquist said. 'It is still a frontline system. It was designed specifically to contain this kind of damage.'
Each gun turret is a massive steel barrel that runs from the bottom of the ship to the top deck and houses three guns. It is divided into compartments on six separate decks and the top part of the turret is sealed off from the bottom level and at various rooms.
Seaquist said it would be wrong to say that the sailors aboard the Iowa were trapped in a 'steel coffin,' saying the turret has several escape hatches. But he also acknowledged that the sailors probably did not have much time.
'Six hundred-sixty pounds of black powder is going to go very quickly,' he said.
Although he would not comment on details of the Iowa accident, he said it is normal operating procedure for officers to order the 'flooding' of the powder magazines in the event of an explosion or fire on the top part of the gun turret. The Iowa's turret was apparently flooded following the explosion.
'Overhead shower sprinklers are turned on,' he explained.
President Bush, a World War II Navy pilot, called the disaster a 'great tragedy' and a 'matter of terrible sadness.'
The death toll made it one of the worst U.S. naval accidents in recent history.
In 1967, 134 people were killed aboard the aircraft carrier USS Forrestal off the coast of Vietnam when a rocket fired from an aircraft on deck started a huge blaze. The next worst accident was in 1963 when the submarine USS Thresher sank with 129 people aboard, followed by 99 dead in the loss of the submarine USS Scorpion in 1968.
Many of the Iowa's dead were inside the gun turret when it exploded and burst into flames. The turret is made of 16-inch armor plate and contained the blast without causing external damage to the ship, a Navy spokesman said.
The 16-inch shells are about 4.5-foot long and weigh 2,300 pounds - 'the size of Volkswagens.'
The last U.S. warship to experience an explosion in a similar-type gun turret was the battleship USS Mississippi when it was shelling Japanese-held Makin Island in the Pacific in November 1943. That explosion killed 43 sailors.
The Iowa has nine 16-inch guns, 12 5-inch guns and also Tomahawk and Harpoon missiles.
The Iowa was one of four battleships that were modernized and brought back into service by the Reagan administration. The Iowa-class battleships, the second largest battleships ever built, all saw action in World War II and Korea and were then 'mothballed.'
All four recommissioned ships -- the Iowa, New Jersey, Missouri and Wisconsin -- were modernized in the 1980s and provided with Tomahawk, Harpoon and Phalanx weapons systems.
The Iowa, first launched in August 1942, won nine battle stars in World War II and two battle stars in Korea. Following its $400 million modernization, it was sent to the eastern Mediterranean in 1984 and to the Persian Gulf area in 1987 to support U.S. escorts of tankers.