The triple-decked M.V. Salahuddin-2, a ferry carrying about 500 passengers, sank at around midnight on Friday on its way to Patuakhali from Dhaka, officials said.
Divers found the bodies of a woman and a child on Saturday and pulled more than 70 survivors from the turbulent Meghna River, keeping their fingers crossed for further rescues.
Officials said the death toll could reach the hundreds once the ferry is lifted from the river bottom, which is not expected until Sunday, which would make it one of the worst river tragedies Bangladesh has known.
Motahar Hossain, joint director of the Bangladesh Inland Water Transport Authority (BIWTA), said one rescue vessel arrived at the disaster scene on Saturday and another was on its way.