The three were shot dead from close range, the sources said.
One of the victims was identified as a member of NSCN (K) while the identity of two others was yet to be ascertained, they said.
There have been reports of intermittent armed clashes between NSCN(K) led by S S Khaplang and Khole-Kitovi led GPRN/NSCN in different parts of the state for the past couple of months.
