SEOUL, South Korea - Word that a South Korean naval ship sank in the tense waters around the disputed maritime border with communist North Korea set off panic: The president convened an emergency meeting, and the military dispatched a fleet of ships.
Five hours later, 58 sailors had been pulled to safety but some 40 others were missing, reports said. There was no indication early Saturday that North Korea was to blame for the ship's demise, but troops kept a vigilant watch.
Seoul's panic attack - hours after North Korea's military threatened "unpredictable strikes" against the United States and South Korea - highlighted the fragility of peace on the divided Korean peninsula.
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.
Since then, the two Koreas have fought three bloody skirmishes in the Yellow Sea waters. And in January, North Korea fired about 30 artillery rounds not far from South Korea's Baeknyeong Island; the South Korean military fired 100 warning shots in response.
The 1,200-ton Cheonan was on a routine patrol near Baeknyeong Friday night with 104 crew members on board when the ship began taking on water, Rear Adm. Lee Ki-sik of the South's Joint Chiefs of Staff told reporters.
Military officials told South Korea's Yonhap News Agency an explosion tore a hole in the rear hull, shutting off the engine, wiping out the power and quickly taking the ship down.