The accident occurred soon after the train left the Dulhazara station in Chakaria Upazila
Kotwali police said FV Monir's engine burst on Saturday morning near the Fisheries Ghat where it was anchored.
Md Liton, 30, 'Nuruddiin', 43, and Md Akbar, 20, on board the vessel sustained burn injuries in Saturday's accident.
Md Alamgir, 45, was hurt as he tried to get out of the vessel in a hurry.