Led by district Superintendent of Police Siladitya Chetia, a joint police and CRPF operation raided the unit near Milijuli market under Baghbar police station last night, Additional SP Satya Ranjan Saikia told reporters here.
Ten hand-made pistols, two guns, and tools for making arms and ammunition were seized from the factory and four persons were arrested.
Of the four, two are from Bihar and the rest from Barpeta district.
Stating that the riverine ('char') areas in the state have became a haven for criminals, Saikia said the arms factory was set up at Baghbar with the help of the persons hailing from Bihar.