BAENGNYEONG ISLAND, South Korea - Hopes faded Saturday for the rescue of 46 sailors missing 12 hours after an explosion occurred on a South Korean military ship that sank in one of the country's worst naval disasters, even as authorities continued searching the murky waters near the sea border with rival North Korea.
Navy and coast guard vessels, as well as air force planes, were combing the waters near South Korea's Baengnyeong Island where the 1,200-ton Cheonan sank early Saturday in bad weather and rough waves during a routine patrolling mission.
The Joint Chiefs of Staff said an explosion tore a hole into the Cheonan's rear hull late Friday night, shutting off the engine, wiping out the power and taking the ship down a little over three hours later. Officials weren't more specific about where on the ship the explosion occurred.
Most of the vessel was underwater Saturday, though the ship's hull was visible. Officials have yet to confirm any deaths. Some of the rescued were treated for burns, broken bones and abrasions, but none of the injuries was considered life-threatening.
President Lee Myung-bak ordered officials to quickly determine what caused the ship to sink, presidential spokeswoman Kim Eun-hye said.
There was no indication North Korea -- which lies some 10 miles from Baengnyeong Island -- was to blame, but troops kept a vigilant watch.
Lee reconvened a security meeting and instructed officials to make all efforts to rescue the missing sailors, the spokeswoman said. Kim added there were no signs of North Korean troop movements.
A number of crew members jumped into the water after the explosion, according to the Joint Chiefs of Staff, which said rescuers had picked up 58 sailors but 46 still were missing.
"The sound of people screaming filled the air," Kim Jin-ho, a seaman on a local passenger ship to Baengnyeong, told cable news channel YTN. "Marines on deck were desperately shouting: 'Save me!"'
Hopes for the missing were diminishing with each hour, a coast guard official said. He said humans can survive in winter waters if rescued within two hours, noting that the temperatures of the Yellow Sea at the time was between 37 and 41 degrees Fahrenheit.
He asked not to be identified because of sensitivity of the issue.
Joint Chiefs of Staff spokesman Park Seong-woo said the military will issue a judgment on the cause of the accident after rescue teams search and salvage the vessel for analysis.
The incident is one of worst naval disasters for South Korea. Local media reported that the country's worst maritime accident occurred in 1974, when a ship sank off the southeast coast in stormy weather, killing 159 sailors and coast guard personnel. In 1967, 39 sailors were killed by North Korean artillery.
A South Korean ship on the same patrol mission with the Cheonan fired shots toward an unidentified target in the direction of North Korea on Friday night, but the object detected by radar may have been a flock of birds, according to the JCS.
Some senior government officials have speculated the sinking may have been an accident, not an attack, South Korean media said. Some analysts also shared that view.
"It's looking more and more like it was just an accident that happens on a ship," Carl Baker, an expert on Korean military relations at the Pacific Forum CSIS think tank in Honolulu, said by telephone. He said Pyongyang was unlikely to attack the far more powerful South Korean military.
The ship went down near a dispute maritime border that has been a flashpoint between the two Koreas. Their military have fought three bloody skirmishes in the area in recent years. The South Korean military uses Baengnyeong Island, the closest South Korean territory to the North, as a military outpost.
Earlier Friday, North Korea's military threatened "unpredictable strikes" against the U.S. and South Korea in anger over a report the two countries plan to prepare for possible instability in the totalitarian country.
The two Koreas remain locked in a state of war because their three-year conflict ended in a truce, not a peace treaty, in 1953.