The suspected People's Liberation Army militants were detected by personnel of the Assam Rifles on patrol at Khoibu hill village under Tengnoupal police station, about 150 km from here, and there was an exchange of fire lasting an hour last evening, the reports said.
Two securitymen and the boy, identified as T Mosel, were injured and a house was destroyed in a grenade explosion during the encounter after which the militants escaped, the reports said.
Clothes were recovered from the encounter site, which was still cordoned off this morning.
The injured were hospitalised.