An Assam Rifles trooper was killed when militants fired at a patrol party here in the Nagaland capital on Saturday, officials said.
The incident took place around 1 p.m. near the Red Cross office in Kohima.
"Our troops were patrolling the area when the militants came and started firing at them. Rifleman A.K. Rawat sustained four bullet injuries," an Assam Rifles spokesman said.
The injured man was taken to a hospital immediately but doctors declared him dead.
The militants had also lobbed a grenade, but it did not explode.
A massive combing operation was later launched by the security forces in and around Kohima.
Security forces suspect the National Socialist Council of Nagaland faction led by S.S. Khaplang (NSCN-K) to be behind the incident.
The faction, which had last month unilaterally abrogated the ceasefire agreement with the central government, had warned of targeting the security forces.
On April 2, suspected NSCN-K militants ambushed an army convoy in Tirap district of Arunachal Pradesh, killing three soldiers and injuring three others.