At least three soldiers were killed after armed militants fired at an army convoy in Assam's Tinsukia district on Saturday morning, defence officials said.Defence spokesman Lt. Col. Suneet Newton said the armed militants first triggered an improvised explosive device (IED) blast before the vehicle was attacked with indiscriminate firing.The incident took place in Pengeri around 5.30 a.m."Four soldiers were injured during the firing. We rushed them to a local hospital but three of them succumbed to their injuries later," Newton said.Tinsukia Superintendent of Police, Mugdhajyoti Mahanta, said the perpetrators of the incident were the National Socialist Council of Nagaland-Khaplang (NSCN-K) and an anti-talk faction of the United Liberation Front of Asom (ULFA) militant group."The militants attacked the convoy with AK-47, RPG, Lethod guns and other sophisticated arms," the spokesperson added.On Wednesday, the suspected militants fired upon a garden vehicle in Pengeri killing one person and injuring two others.