South Korean troops have cornered a soldier who shot dead five colleagues and fled his post near North Korea's border, sparking a massive manhunt.

One soldier was injured as the renegade conscript exchanged fire with troops hunting him in the border town of Goseong, Gangwon province, reports say.

It is not clear why the sergeant, identified only by his surname, Im, had opened fire on Saturday evening.

There have been similar shooting cases in the South Korean army in the past.

The stand-off, near a primary school, may be aimed at allowing the military to negotiate the renegade soldier's surrender, says the BBC's Kevin Kim in Seoul.

One media report said the conscript's parents had been taken to the site to help convince their son to turn himself in.

Guarding the demilitarised zone, which divides the two Koreas, is considered one of the toughest jobs for military conscripts, adds our correspondent.

'Difficulties adapting'

Sgt Im shot fellow members of his 22nd infantry division in the remote guard post and then escaped with his semi-automatic K2 rifle and some ammunition, army officials said.

Sgt Im "threw a grenade and then opened fire" after completing his day shift, Yonhap reported.

Seven other troops were injured in the incident, but are expected to survive.

Thousands of troops were deployed to block possible escape routes, guard the border between North and South Korea, and protect areas where civilians live, officials said.

An officer said Sgt Im "was on the list of those who require special attention, as he had difficulties in adapting to the military life," the South Korean news agency reported, adding that he had been due to be discharged in three months.

The defence ministry spokesman said the incident was "regrettable", adding: "We truly apologise for causing concern to the nation."

There have been similar incidents in South Korea's military, which operates under a conscription system. Bullying and mental problems have been blamed for previous attacks.

In 2011, a marine opened fire on his colleagues and tried to blow himself up with a grenade. Four soldiers were killed in the attack.

Tens of thousands of soldiers from both North and South Korea are stationed along their joint border, one of the most heavily fortified in the world.

The two Koreas were divided at the end of the 1950-53 Korean War, which ended in an armistice rather than a peace treaty. As a result, they remain technically at war.

Source: BBC