The militants exploded a bomb before firing at the army vehicles along the Longding-Kanubari road forcing the army personnel to retaliate, army sources said.
However, there was no report of any casualty and neither it could be established whether the militants belonged to the proscribed NSCN (IM) or ULFA, the sources said.
In a statement, Arunachal Pradesh Home Minister Tanga Byaling termed the incident as "unfortunate and condemnable".
He said that the army personnel were on duty for the security and safety of the people and the underground group had no reason to resort to an anti-national act.
Kanubari MLA Gabriel D Wangsu said that the ultras ambushed the convoy near a remote post when the personnel were on their way back to a post after routine patrolling duty.