A lighter vessel carrying goods sank in the dry dock area of the Karnaphuli River in Chattogram city last night.
The name of the vessel and the reason behind the incident could not be known immediately.
Ratan Khan, an official of Coast Guard at Sadarghat in the port city, confirmed the incident saying that a rescue team was sent to the spot.
All crew members of the vessel were rescued, he said.
A resident of the area said he witnessed the vessel sinking at the dry dock area around 9:45 pm.
Before sinking, six to seven crew members of the vessel managed to board an engine-run boat and another swam ashore, he said.
Primarily, it is being assumed that the vessel sank due to a leak, the witness added.