SEOUL A South Korean marine went on a shooting spree on Monday at a base near the tense maritime border with North Korea, killing four fellow soldiers before trying to blow himself up with a hand grenade, the military said.
The incident was not related to the ongoing inter-Korean conflict which has simmered since 1953 when the Korean War ended in a truce, not a peace treaty.
A fifth soldier was injured in the attack.
"After firing his K-2 rifle inside the marines' living quarters, a hand grenade was detonated in a separate building compartment outside," marine's spokesman Colonel Kim Tae-Eun told a press briefing.
"No one else was present in the compartment aside from the shooter Corporal Kim."
The shooting took place at a base on Gangwha Island off the divided peninsula's west coast, the scene of numerous incidents between the rival Koreas in recent years.
It was not immediately clear what motivated the marine's actions.
In a similar incident in 2005, a South Korean private killed eight soldiers when he threw a hand grenade inside a border post barracks and fired dozens of gunshots.
Military service is compulsory in the South for all young men.
Seoul has boosted its military presence in the West Sea area after blaming North Korea for two deadly attacks last year. It has warned of a swift and decisive response in the event of further armed aggression by its neighbor.
A total of 50 South Koreans were killed in last year's attacks -- the first involved the torpedoing of a South Korean warship while in the second an island was shelled.
The North denies it was behind the ship sinking and said it was provoked into shelling the island by a South military drill in the area.
(Reporting by Jeremy Laurence and Joonhee Yu; Editing by Sanjeev Miglani)