The deceased, identified as Kamlesh Dhanu (25) and Sanjay Bhidia (20), both residents of Uttar Pradesh, had entered the effluent treatment plant (ETP) of a private company, a snack foods conglomerate, to clean it, Deputy Chief Fire Officer B R Verma said.
The five workers had entered the plant and one of them went deep inside and fell unconscious immediately because of the emanating gas, Verma said.
To rescue his colleague, another worker went further inside and when both of them were brought out, they had died, he said.
Three others who had gone inside were rescued and given treatment on the spot, Verma said, adding that one of them had to be taken to a hospital.