The jawans of the COBRA unit were ambushed in the IED blast after which an encounter started between the two resulting in the killing of three naxals, they said.
The incident was reported from Chakarbanda forests of the said district, bordering Imamganj.
Some arms and ammunition were also recovered from the site.
Officials said the casualties may rise as some of the jawans of the Commando Battalion for Resolute Action (COBRA) were critically injured in a fierce gun battle, which was still raging.
Officials said the mobile phone connectivity is very bad in the area hence much information is not trickling out.
The jawans belonged to the 205th COBRA battalion and were deployed in the state for conducting anti-naxal operations.
This is one of the biggest casualties of the elite COBRA unit which has been raised by the CRPF for undertaking special jungle warfare operations.