Though the driver had papers for 130 packets of gelatin sticks which the truck was also carrying, he did not have papers for the 97 detonators, they said.
The truck was intercepted on Saturday night when it was going to Pakur from Khunti.
Besides the driver and helper, a woman was also arrested, they said.
The police did not rule out the possibility of the detonators being sent for Maoists.