The pastor and his companions had left for Bettiah from Bagaha in the district in a bus to participate in a special prayer meeting at the Protestant church James Saint Paul's here, Superintendent of Police Jayant Kant said.
After it reached the bus stand here, a person in the vehicle attacked the pastor claiming he converts people. The accused also rang up others asking them to reach the bus stand, the police said.
However, the attackers managed to flee.
An FIR has been registered and further action would be initiated if the pastor or anyone of his group registers a complaint, the police officer said, adding those involved in the attack would not be spared.