The truck, carrying cosmetics of a reputed private company, was hijacked by a gang of dacoits when the vehicle was on its way to Kolkata from a plant in Doomdooma town about 20 days ago, Tinsukia Superintendent of Police A P Tiwari said.
The nine members were arrested from Dhubri, Gossaigaon and Nagaoan in Assam, Asansol in West Bengal and Andhra Pradesh in the pas few days, he said.
The police also recovered the truck.