Sub-inspector (SI) of Kotwali model police station Md Jamal filed another case accusing the attackers for obstructing police to carry out their duties and launching attacks on them.
UNO Munibur Rahman confirmed the development to Prothom Alo on Thursday evening.
Barishal Metropolitan Police deputy commissioner (south) Ali Ashraf Mia also said Serniabat Sadiq Abdullah has been made an accused in the case filed by the UNO.
Legal action would be taken following investigation, he added.
UNO Munibur Rahman said posters of state minister for water resources Col. Zaheed Farooque were hung up to commemorate the National Mourning Day at different places on the upazila parishad premises. Bangladesh Chhatra League (BCL) men came to tear down those at night.
The UNO asked them to tear down the posters on Thursday morning as people were sleeping then. But the BCL men abused him verbally and started picketing around his residence, he added.
Some Ansar members deployed at the security of UNO’s residence were injured at the attack.
BCL, however, claimed that at least 30 of their leaders and activists sustained bullet injuries.
Meanwhile, Barishal district and city unit Awami League claimed that no one carried out attacks on UNO’s residence and alleged that the incident was a pre-planned one.
They also sought a judicial probe over the incident.
The bus services in Barishal and other parts of the country had remained suspended since Thursday morning as transport workers blocked the Dhaka-Barishal highway in protest against Wednesday's clash, UNB reports.
Barishal Deputy Commissioner (DC) Jasim Uddin Haider said that 10 platoons of the Border Guards Bangladesh would be deployed in the city to prevent further deterioration of law and order.
He also added that ten executive magistrates may also arrive in Barishal from surrounding districts to help the local local administration to maintain law and order.