The operation was conducted against an ULFA faction opposed to peace talks.
A police spokesman said an ULFA guerrilla was captured in the Jorhat district and armaments captured.
ULFA rejectionist cadre Raju Saikia said the police operation resulted in the capture of ULFA militant Rajat Dutta, while other ULFA members managed to escape in the darkness.
Munitions seized by the police included nine landmines, one M81 rifle, one AK-47 rifle and 90 rounds of ammunition, magazines, six bombs and five remote controls, the Assam Tribune reported Thursday.
Police said the operation began when a truck was signaled to stop for a check on the highway on the outskirts of Jorhat but that it failed to do so and sped away, being later caught in Bongalpukhuri, where Dutta and the armaments were taken into custody.
A police official speaking on condition of anonymity said: "The police team arrested the two persons. Some more cadres of the outfit managed to escape."