At least 50 people were injured in a clash between Awami League and the BNP in Bahria Bazar area under sadar upazila in Chandpur, during the last day of the 60-hour hartal on Wednesday morning.
Meanwhile police detained 12 people while picketing in different areas of the district.
Police and witness sources said BNP leaders and activists came out in a procession in support of the hartal and vandalised shops at around 10am. They clashed later with ruling party members who brought out a counter procession, 50 people were left injured.
The injured were admitted to different clinics, including Chandpur Sadar Hospital.
Awami League activists set fire to the local office of the BNP.
Police Super Amir Jafar said police fired a few rounds of tear shells to bring the situation under control and deployed Border Guard Bangladesh to avoid further trouble. He said three people were detained in connection with the incident.
Police also held five Shibir activists during a clash between Jamaat-e-Islami / Chhatra Shibir members and the police in front of Government College around 11:30am.
Sadar model police station Officer-in-charge Mahbub Murshed said: “Pickets vandalised a police vehicle and set off a few crude bombs during the clash.”
Police also detained four BNP leaders while picketing in Chandpur-Kuchua road in the morning.