Superintendent of Police Jitender Rana told PTI that armed Maoists blew up a PWD building by exploding bombs in Parasi village of the district.
When a STF patrol party was on way to the incident site, the Maoists opened fire on them from a mountain top in which three STF jawans were critically injured.
One of them succumbed to his injuries later on while two others are admitted in a government hospital.
Additional police force has been rushed to the spot and combing operation is on.