Police said rescuers rushed to the scene where the MV Coco-4 sank in the Tetulia river near the town of Lalmohan in Bhola district some 300 km (219 miles) south of Dhaka.
The ferry sank as it listed to one side when passengers were disembarking at a ferry terminal, the police said.
“The casualties may be more as the lower deck of the triple-decker ferry sank,” a police officer at the scene said. The exact number of passengers was not available as ferry authorities often do not keep passenger lists, he said.
Passengers had ignored warnings and gone aboard the crowded ferry to get home ahead of festival on Saturday.
“At festival time it is really difficult to stop passengers and relevant ferry operators from flouting rules,” an officer from the inland water transport authority said.
Fire service divers searched for more bodies and a rescue ship had been called in to salvage the sunken ferry, the emergency services said.
Hundreds of people used to die every year in ferry accidents in Bangladesh, but no major ferry disasters have happened in the past two years after stricter enforcing of safety rules.
