One more member of the gang, allegedly involved in the incident, was absconding and search was on to nab him, said Inspector in-charge of Goshaninuagaon police station, S S Mohapatra.
The arrested persons are Rohita Pradhan, Suman Padhy, Chikun Panda, Jagannath Mishra, Durga Prasad Panigrahi, Babu Padhihari and Kasinath Padhy, all aged between 19 and 22 years and hailing from Goshaninuagon, he said.
Previous enmity with an auto-rickshaw driver was stated to be the cause of the bomb blast near the railway station on January 13 night, police said.