Karbi Anglong Superintendent of Police Debajot Deuri said the militants belonged to the Karbi Peoples Liberation Tigers or KPLT-S. A soldier was also injured in the gun battle.
An INSAS rifle, a self-loading rifle, three pistols, a gun and two grenades were recovered from the dead men.
"An army unit raided a remote location on Thursday night. They spotted some suspicious movement. The militants fired at the forces, leading to a gun battle on Friday," Deuri said.
The KPLT-S is a splinter group of KPLT. The group is involved in several extortion activities in and around Karbi Anglong district.
Terming it as one of the biggest operations in the fight against terror in northeast India in recent times, a defence spokesperson said the army carried out "a swift and surgical joint operation" with personnel of the Assam Police based on specific hard intelligence in the dense Nambar Reserve Forest.
"The six terrorists neutralised include a self-styled Operation Commander and Area Commander of KPLT. A large quantity of arms, ammunition and other warlike stores were recovered from the terrorist camp," he said.
"The recoveries included one INSAS Rifle, one 7.62 mm Self-Loading Rifle, one country-made rifle, hand grenades, large quantity of ammunition of all types, fired cases, solar chargers, blankets and other war like and survival stores," he said.
The army claimed the operation has led to the near decimation of KPLT.
