The incident happened at 10:30 am at the Hathi Char border post along the Indo-Bangladesh border.
The jawan Prabhakar Mishra allegedly shot the officials and colleagues from his service weapon and later shot himself. Mishra succumbed to his injuries on way to hospital, a senior official said.
The two dead are Assistant Sub-inspector rank officers -- Babu Lal and Surender -- of the force. The injured has been identified as constable Om Prakash, the official said.
The exact reason for the incident is yet to be ascertained but it seems that Mishra was under stress and had some heated exchange with the officials before turning the gun on them and later on himself, the official said.
Senior officials of the paramilitary force have rushed to the border post which is close to the Brahmaputra River.
This incident is the third fratricide incident in the last few months in the border guarding force as earlier incidents were reported from Punjab and Rajasthan. The Border Security Force (BSF) is manning the Indo-Bangla border in this region.