Assam Police have killed a United Liberation Front of Assam (ULFA) militant and arrested three others.
Police said they were informed about the activities of the ant-social elements around Goalpara district, which borders Meghalaya.
According to the police, two or three militants were also injured, but they managed to escape.
Two pistols, three cell phones, two pairs of shoes and a wallet containing money were seized from the arrested militants.
Police said that the operation was still underway.
"I have told you that the operation is going on. Yes we have recovered some weapons, but we can't say now. The operation is still fully going on. After conclusion of operation we will be able to tell you," said A.P. Tiwari, Senior Superintendent of Police.
Tiwari added that three AK-81 rifles, nine magazines and three US-made bottle grenades were seized from them and the arms were being taken to Goalpara district.
ULFA, the top militant group fighting in the country's remote northeast for almost three decades.
More than a dozen insurgent groups have been fighting the government for decades in Assam and neighbouring states of northeast India, killing thousands in attacks on civilian troops and paramilitary.
The groups blame the government of plundering the region's significant mineral and agricultural resources and ignoring demands for greater autonomy and greater economic opportunities.
