The Naxals blasted railway tracks between Daniya and Dumari Bihar stations in Jharkhand's Bokaro district late last night.
The Naxals then attacked the party that was proceeding to the spot to repair the damaged portion of the track.
One RPF Jawan has been shot dead by Naxals.
This line serves mostly local trains, and so a few of them are held up. One express train, the Howrah-Mumbai mail has also been held up.