Acting on a tip-off about presence of three ULFA militants, soldiers from Army's 5 J&K Light Infantry and police personnel cordoned off Nazirapuriya village near Khowang town at around 2.30 pm, official sources said.
As the forces advanced on the village, the ULFA militants fired from a house. A police informer, Papuna Prasad Thakuria, was hit by bullets and died on the spot, the sources said.
Thakuria, a surrendered ULFA militant, is suspected of having given the tip-off but officials remain tight-lipped on the issue.
During the gunfight, Officer-in-Charge of Moran police station Utpal Bora was also injured. Bora, who received a bullet in his right hand, is currently undergoing treatment at the Dibrugarh Medical College.
However, the ULFA militants managed to flee from the area. A search has been launched to nab them.
Army and police seized three grenades and two motorcycles from the encounter spot.
Four villagers have been picked up on suspicion of having provided shelter to the ULFA militants.
