Dhaka, Bangladesh ? Rescue crews scoured a turbulent river today in search of more than 500 passengers missing and feared dead after an overcrowded ferry capsized in southern Bangladesh.

Strong currents hampered the search for the triple-deck ferry, which sank Tuesday night with about 750 people on board at the meeting point of the Padma, Meghna and Dakatia rivers. The vessel went down as it approached a ferry terminal in Chandpur, a town about 40 miles south of the capital, Dhaka.

As hundreds of anxious relatives and survivors lined the shores or joined the search, fishermen with nets and divers combed the rough waters.

Two salvage ships with cranes were at the scene. Once the ferry, the MV Nasreen, is found, they will attempt to lift it from under 200 feet of water. said Manzoor-e-Elahi, a government administrator.

Four bodies have so far been found, rescue officials said. They feared many more bodies were trapped inside the ferry, which still had not been located.

Many of the passengers were sleeping when the overcrowded ferry capsized. About 220 people either swam to shore or were rescued by fishermen.

The exact number of passengers who boarded the ferry was not known, but rescue officials believed about 530 people were missing. Ferries in Bangladesh do not carry passenger lists, and many people buy tickets after boarding.