It was also not known whether the insurgents exploded the bomb by using remote-controlled device or timer but official sources said it was a powerful bomb of improvised explosive device (IED). The sound of explosion could be heard at a distance of 3 km.
First official reports said Assam Rifles personnel opened fire seconds after the explosion at the hill side where they thought insurgents were fleeing.
Reports said two civilians, identified as Sangaijao Singh and Kaboklei, who were working nearby were injured but it was not immediately known whether they sustained injuries by the splinters of the bomb or in the exchange of fire between Assam Rifles personnel and insurgents.
Official sources said Sangaijao Singh died of his injuries while the injured were taken to a nearby hospital at the border town of Moreh, about 3 km from the spot.
Sources said a large number of police and other security forces from Moreh rushed to the spot for a massive manhunt but no one was arrested so far. Insurgents reportedly escaped to nearby thick jungles, sources said.
No individual or group has claimed responsibility for the incident but banned People's Liberation Army (PLA) have been attacking security personnel at different places in the past one by exploding bombs more than five times this month.