The incident happened late last night at Magurbari under Kokrajhar police station.
Two armed men came in a bike to the house of Mohibul Islam, who is the founder president of the ABMSU, and fired at him.
Abdul Siddique Sheikh, a former president of the Bilasipara unit of the All Assam Minority Students' Union (AAMSU), who was present there was also seriously injured.
Both were rushed to a local hospital and shifted to the Guwahati Medical College this morning.
Meanwhile, police today have recovered a bike and a pistol from a field in Hagrabari, which is about one kilometre from the incident site.
Police official said the bike and the pistol were used by the assailants during the attack.
