Rebels killed five paramilitary men, including two officers, in an ambush in Manipur on Monday, security officials said.
The incident took place in a remote village in Chandel district, about 120 km (75 miles) south of Imphal, the capital of mountainous revolt-racked Manipur, sharing border with Myanmar.
"Militants fired on the vehicle from hilltops and killed all five of them on the spot. When our reinforcement reached the spot they found the bodies lying there," a senior military commander told Reuters on condition of anonymity.
The powerful United National Liberation Front (UNLF) fighting for freedom in the state claimed responsibility of the attack.
Security officials said the rebels fled to Myanmar after the strike.
Manipur, a state with a little more than two million people, has suffered separatist and tribal insurgencies for the past 60 years.
Thousands have died due to prolonged insurgency in Manipur in the past few decades. Armed groups active in region accuse New Delhi of plundering the region's mineral and forest resources but investing little in return.