Superintendent of Police Nitul Gogoi said in the wake of the blast at Dudhnoi, police stepped up vigil and received a tip-off about a group of ULFA (Independent) militants moving in Krishnai area of Goalpara district.
Officer in charge of Krishnai police station, along with commandos, surrounded a house at Jira where the ultras were holed up and cordoned off the area, Gogoi said.
One of the police commandos died when the insurgents opened fire and in the ensuing gunbattle, one of the militants was also killed, he said.
Three pistols, an AK rifle magazine, a grenade and several extortion notices were also recovered from the slain rebel.
The SP said last night's bomb blast that killed three persons and injured 20 others was not connected with the ongoing Assam Assembly elections as the militants took advantage of the forces moving out for deployment from the areas where first phase poll was held yesterday.
Director General of Police Mukesh Sahay told reporters in Goalpara, "There may be possiblility of violent incidents during the second phase of elections but we are prepared to tackle such attempts".