A corporal in South Korea's marine corps went on shooting rampage Monday, killing four fellow marines and wounding another on a Yellow Sea island base near the country's tense border with North Korea, officials said.
The corporal was taken into custody on Ganghwa Island, about 40 miles west of Seoul, but his motive remained unknown, and the shooting was being investigated, Defense Ministry officials said.
The country's Yonhap news agency quoted sources who said the soldier later went inside a guard post and detonated a hand grenade in an apparent suicide attempt and sustained severe injuries.
The corporal, surnamed Kim, was also wounded, but it was unclear whether he tried to kill himself or was hurt when he was apprehended, the officials said. They declined to give their names citing office policy.
One of the slain marines was an officer, while the others were rank-and-file marines, the officials said.
Marines in frontline
The weapon in the shooting could not be identified immediately, officials said.
South Korea stations hundreds of marines on front-line islands within easy striking distance of North Korea.
Last year, North Korea shelled a South Korean island, killing two civilians and two marines.
The waters are claimed by both countries. Boats routinely jostle for position during crab-catching season, and three deadly naval clashes since 1999 have taken a few dozen lives.
The tension has taken a toll on South Korea's marines, who would take the brunt of any North Korean attack.
The South Korean military has beefed up marines' combat readiness on a cluster of bases in the Yellow Sea and increased high-tech weapons systems on the islands facing the North.
The latest shooting is the worst to happen in South Korea's military since 2005, when a soldier tossed a hand grenade and opened fire at a front-line army unit in a shooting rampage that left eight colleagues dead and several others injured.
Pfc. Kim Dong-min later told investigators he went on the killing spree after being enraged by superiors who verbally assaulted him.
The shooting raised questions about the level of discipline in South Korea's 650,000-member military.
All able-bodied South Korean men must serve about two years in the military under a conscription system aimed at deterring aggression from North Korea.