The incident took place when the driver of the car, carrying the trader, had stopped the vehicle near Basauni Mor under Panjwara police station area.
The trader was walking after alighting from the vehicle when the miscreants snatched the bag at gun point and escaped from the scene, Panjwara police station officer-in-charge Vimal Kumar Das said.
The medicine trader Rupak Yadav, who runs a medicine shop in Godda district of Jharkhand, was on way to Bhagalpur to buy medicines, Das said.