SEOUL, March 27 (UPI) -- As many as 46 sailors were missing after an unidentified object sank a South Korean navy ship near the western sea border with North Korea, officials said.
Another 58 crew members were rescued after the 1,200-ton patrol ship Cheonan sank Friday night about a mile from South Korea's northernmost island of Baengnyeong in the Yellow Sea.
Naval officials narrowed the cause of the sinking to a rock, a torpedo attack from outside forces, including North Korea, or an internal explosion caused by the ship's weapons, the Yonhap News Agency reported Saturday.
Strong currents and rough seas hampered rescue efforts Saturday as military divers and surface ships searched for crew members, Yonhap reported.
The South Korean coast guard was on its highest alert and President Lee Myung-bak's office said nothing had been confirmed about possible North Korean involvement. North Korea's officials were silent about the sinking, one of the worst tragedies in South Korean naval history.