An Indian paramilitary soldier shot and killed six of his colleagues with an assault rifle, then fled their military camp in a remote and dangerous outpost in northeastern India, the military said Thursday.

Officials are investigating the Wednesday night shooting and have launched a manhunt for the soldier, a member of the Assam Rifles paramilitary troop whose name was not immediately released, said Maj. Shamsher Jung, an Assam Rifles spokesman.

"The trooper first trained his assault rifle on a senior officer following an argument, killing him. When five fellow troopers rushed in after hearing gunshots, the berserk soldier sprayed bullets on them," said Jung.

It was not clear what prompted the killings in Ukhrul district, 55 miles northeast of the state capital of Imphal, Jung said.

It was the sixth time in three years that a soldier posted to the insurgency-wracked state of Manipur has fired on other Indian forces.

Violence between fellow soldiers is not unusual in India and is often attributed to stress and exhaustion after long postings.

Manipur, one of India's most remote and dangerous regions, can be an especially grim assignment.

The Assam Rifles are fighting separatist rebels who straddle the heavily wooded and porous India-Myanmar border. More than 10,000 people have died in separatist violence over the past decade.

The rebels accuse authorities of exploiting the area's natural resources while doing little for the indigenous people — most of whom are ethnically closer to Burma and China than to the rest of India.