Superintendent of Police Vikas Barman said that 10 people have been detained in this connection.
Investigation is underway to ascertain whether the arms seized are legal or not, the SP said.
The raid was a joint operation of Forest Department officials, Sashashtra Seema Bal (SSB) and local police, he said.
Sipahi village, under Rajauli police station limits, has sheltered Maoists.