A low intensity explosive kept in the side box of Vijay Shankar Singh's motorcycle went off at Kargahar crossing on old GT Road just opposite the court premises at around 3 PM, the DGP control room said in a statement.
The object appeared to be a detonator which exploded accidentally, the statement said, adding Singh is a carrier of banned Maoist outfit Tritiya Prastuti Committee.
However, Rohtas district Superintendent of Police Manavjeet Singh Dhillon said a pamphlet purportedly left behind by Maoists was recovered from the spot and it claimed responsibility for the explosion over non-payment of levy by Singh.
"Objectionable" materials, including letters for levy demand, has been recovered from the possession of Singh, the statement said.
Senior police officials went to the spot to probe the incident.
The SP said a forensic team was on its way to collect evidences related to explosion.