The exchange of fire occurred in Kanaguda forest in Kalimela area when jawans of elite anti-Naxal Special Operation Group (SOG) were returning after combing operations, Superintendent of Police Anirudh Singh said.
The ultras first exploded claymore mines when the jawans were returning, some of them on motor-cycles, and then fired at them, he said.
The security personnel also retaliated and in the exchange of fire that ensued three SOG jawans were injured, the SP said adding two of them were admitted to a hospital at Kalimela while another was shifted to the district headquarters hospital where his condition was stated to be critical.
When BSF jawans and district police personnel went to the site after the encounter, the red rebels disappeared into dense forest.
Maoists are observing a protest week since May 23 and have given a call for bandh on May 30 demanding halt to Green Hunt operation by security forces.
