Over 200 personnel of Bihar Police and CRPF took part in the operation.
Munger Superintendent of Police (SP) Barun Kumar Sinha said, this is the first time that an arms manufacturing unit being operated by the Naxals has been unearthed.
The raid was conducted on the basis of intelligence inputs and ASP(Operations) Navin Kumar led the team. Sinha said the operation was conducted in difficult terrain during the pre-dawn hours.
The forces were not able to apprehend any Naxal as they escaped taking advantage of darkness.