S Korean marine 'kills four on Ganghwa island base'
A South Korean marine has turned his gun on his colleagues, killing four and injuring another, officials say.
A spokesman for the defence ministry in the capital, Seoul, said the corporal had opened fire while on duty at Ganghwa island west of Seoul.
A staff sergeant and two marines died on the spot while another marine died of his injuries on the way to hospital.
The 19-year-old corporal was later wounded by an exploding hand grenade in a possible suicide attempt.
The Ganghwa island base is near a disputed maritime border with North Korea.
All able-bodied South Korean men are required to serve at least two years in the country's 650,000-member military.Grenade
The motive for Monday's shooting on the island 70km (40 miles) west of Seoul remains unclear.
The injuries sustained by the apparent shooter - known only by his surname, Kim - are preventing him from immediately answering questions about the incident, said marine corps spokesman Kim Tae-eun.
"After firing his K-2 rifle inside the marines' living quarters, a hand grenade was detonated in a separate building compartment outside," he told a news briefing.
"No-one else was present in the compartment aside from the shooter Corporal Kim."
He said an investigation was under way.
Numerous incidents between North and South Korea off the peninsula's divided west coast - where the waters are claimed by both sides - have raised tensions for the hundreds of South Korean marines stationed on islands in the area.
There have also been previous violent incidents involving South Korean soldiers in recent years, some linked to claims of bullying by senior officers.
In 2005, a young soldier threw a grenade and fired at sleeping comrades, killing eight and seriously injuring two.
In 2008, a private reportedly injured five other soldiers when he threw a grenade at them while they were sleeping.