The incident occurred last evening at South Point of Zunheboto town when NSCN(K) cadres allegedly started firing and lobbed grenade at a private residence where six members of the rival NSCN(Khole-Kitovi) group were having prayer meeting.
In the firing, a boy aged around 16 to 17 years died on the spot due to bullet injuries. The deceased is the son of the civilian in whose house the prayer was held.
Two other civilians, including a student of Patkai Christian College, Dimapur, were also injured as the gunfight between the two groups continued for about 15 minute, police said.
The condition of the injured was stated to be out of danger.
The NSCN (Khole-Kitovi) sources said one of their cadres was also injured in the firing.
Tension prevailed in Zunheboto district for past couple of months due to turf war following vertical split in the NSCN(K) last year.