According to Malkangiri Superintendent of Police Satyabrata Bhoi, the blast occurred when a van carrying the CRPF personnel was on its way from Kalimela to Gompagunda probably to pick up rations.
Bhoi said, the landmine was planted at a culvert and exploded when the van passed over it.
CRPF deputy commandant Bhupinder Singh was among the three CRPF men killed.
The attack is believed to be part of the Maoist strategy to restrict movement of security forces ahead of their proposed offensive in the region.
Additional CRPF jawans and state police personnel have been rushed to the site, while steps taken for intensifying patrolling in the area, Bhoi added.