Four members of the ULFA, including two women, suspected of masterminding recent bomb attacks in the city were arrested on Saturday, police said.
Police officials in Dibrugarh said three senior leaders of ULFA's "strike force 28th battalion" were arrested at Abhaypur in Sibsagar district as they were travelling from Guwahati to Namrup in Dibrugarh district.
They were identified as Numal Chetia alias Kailash Changmai, a Myanmar-trained "sergeant major", his wife Bonty Chetia and "sergeant major" Samiran Barua alias Bishnu Bora.
Police also nabbed Baby Chetri (30), a member of ULFA's Enigma 'B' unit, near Gauhati Medical College Hospital as she was coming out from the facility after meeting ULFA Vice Chairman Pradeep Gogoi, who is being treated in the hospital.
Officials said Chetri was trained in urban guerrilla warfare and a partner of Numal Chetia. Educated in a missionary school in Guwahati, Chetri was released from jail in September, 2006, Guwahati's Additional Superintendent of Police Rajen Singh said.
Chetia joined the ULFA in 1994 and jumped bail in 2004 after he was arrested following a shootout with police in Dibrugarh district, officials said.
Samiran Barua, the head of ULFA's political wing in upper Assam, joined the group in 1989, while Bonty Chetia had returned to Guwahati from Myanmar after her induction into the outfit in 1996, they said.
Twenty-three people were injured on Friday in Assam in two separate blasts and a shooting attributed to the ULFA.