At least four workers suffered burn injuries in a blast that took place at a shipyard in Sitakunda upazila of Chattogram this afternoon. The incident took place at 2:30 pm when they were working in an engine room of a  ship at SN Corporation in Madambibirhat area of Sitakunda, reports our Chattogram staff correspondent quoting M Abul Kalam Azad, officer-in-charge of Sitakunda