Officer-in-charge (OC) of Sitakunda police station Mohammad Abul Kalam said the four workers were burnt by oxy-acetylene gas fire while working at the shipyard in the morning.
"One of them is now in critical condition while the others sustained minor injuries," he added.
The injured were admitted to Chittagong Medical College Hospital (CMCH). Locals said a tank exploded while workers were working for breaking an imported scrap ship at the shipbreaking yard in the morning.
ASI Alauddin Talukder of CMCH said among the four victims, Sohail Rana and Zahid have been admitted to the burn and plastic surgery ward and the others to orthopedic surgery ward.