Acting on a tip-off, police apprehended Mintu Das and Jotin Das in Williamnagar while they were carrying the arms consignment in a multi-utility vehicle bearing Assam's registration number, IG of Police (Western Range) G H P Raju said.
Three AK series rifles and 150 rounds of ammunition, meant for the Garo National Liberation Army's self-styled commander Sohan D Shira, were recovered from the duo, he said.
Police claimed the trio were members of the United Democratic People's Solidarity (UDPS), a militant organisation active in Assam's Karbi-Anglong district.