A joint police and army team surrounded Dingdang Para village under Khoirabari police station after a tip off that the militant Basiram Bodo was hiding there, police sources said.
The militant fired and the security forces retaliating killing him, the sources said.
A hand grenade, a 9-mm pistol, three live cartridges, several spent cartridges, a mobile handset and documents were recovered from the slain ultra, they added.