The death toll rose to six from the explosion in an oil tanker in Jhalakathi's Suganda River.
Five injured staff of the tanker died at the Sheikh Hasina National Institute of Burn and Plastic Surgery in Dhaka.
The deceased are - Shahid Talukder, 40, Mehedi Hasan, 28, Md Ripon, 40, Md Rony, 27, and Ashikur Rahman, 25.
Dr Samanta Lal Sen, chief coordinator of the Sheikh Hasina National Institute of Burn and Plastic Surgery, confirmed the matter to media.
The victims suffered over 70% burns in the accident. They succumbed to their injuries from Tuesday morning to evening, he added.
Earlier on Friday morning, an explosion took place on an oil tanker vessel "Sagar Nandini-3" in Sugandha river, leaving one crew dead and seven others burnt.
At the time of explosion, the vessel was near Padma Oil Company on the bank of the river.