A cargo vessel carrying 510 tonnes of coal capsized in the Passur river near the Sundarbans in the district's Mongla upazila last night.
Sub-inspector Md Nazrul Islam of Chandpai Navy Police Camp said Khulna-bound cargo ship MV GR Raj from Mongla port sank in the river near Beauty Market area as the keel of the ship was damaged around 9:00pm.
Locals rescued 10 crews of the vessel from the river in a trawler.
A three member investigation committee, headed by Md Belayet Hossain, assistant forest conservator (Chandpai Range) of the forest department, was formed to probe the incident.
Md Saidul Islam, divisional forest officer of Sundarbans (east zone), said the coal might harm the ecosystem of the Sundarbans, the world's largest mangrove forest.
The salvage operation to recover the vessel didn't start till filing of the report around 1:00am today.