Update at 12:55 a.m. ET. The Associated Press now reports from Seoul that:
"Military officials say a South Korean navy ship has sunk off an island not far from North Korea. An official with the Joint Chiefs of Staff in Seoul said early Saturday (local time) that the ship sank some four hours after it began taking on water. The official spoke on condition of anonymity, in line with department policy."
Also from Seoul, Doualy Xaykaothao reports for NPR that South Korea's president held an emergency meeting at the Blue House (South Korea's equivalent of the White House) and that there is an investigation under way into whether the ship was hit by a North Korean torpedo. It's unclear, she adds, whether the reports about a shot being fired by a South Korean vessel refer to the ship that has been sunk or to another South Korean ship in the area.
Our original post:
"A South Korean Navy ship is sinking off the west coast near (the country's) maritime border with North Korea," according to South Korea's Yonhap News Agency, saying it gets that news from South Korean Government officials. It adds that "officials also said South Korea fired a shot at an unidentified vessel toward the North."
Reuters says other South Korean media are reporting that the ship was "possibly ... hit by a North Korean torpedo and (that) several sailors were killed."
The Associated Press reports the ship may already have sunk. Yonhap says it has a crew of 104, and that at least 58 have been rescued.
South Korea's Cabinet is holding an emergency meeting, the news agency also says.