The Maoists triggered the blast near Bandhu Bigaha village when three commandos of CRPF's elite 205th Commando Battalion for Resolute Action (CoBRA) unit were riding on two bikes on way to their camp from Bali Pahari locality, Deputy Superintendent of Police P N Sahu said.
CRPF personnel were engaged in an encounter with the ultras since last night in Bali Pahari.
The blast occurred around noon, officials said.
One commando was killed on the spot while his two other colleagues sustained injuries, Sahu said.
The martyred commando has been identified as A Deka while the injured are A K Yadav and K Kakoti.