The police said the money was being transported from Patna to Jamui, when five to six gunmen travelling in a car forced the cash van to stop near Bhikhua village in Fatuha police station.
"They fired a few bullets to terrorise those carrying the cash, wrenched open the doors of the cash van and loaded the money in their own vehicle. They sped away within minutes with Rs 1 crore was being carried in the van," Fatuha SHO Sanjeev Kumar Sinha said.
Several police teams have been formed and raids were being conducted to arrest the persons involved in the loot.