According to details, a factory worker while cleaning the oil tank in a bio gas factory, slipped in it. Three others went behind him in the oil tank to help him.
The factory workers rescued two workers in an unconscious condition and transferred them to Jinnah Hospital for medical attendance.
The rescue workers retrieved the bodies of two workers, who were drowned in the oil tank to death.
The incident took place due to lack of safety measures in the factory, which is a violation of the labour laws, sources said.