India, May 6 -- Three sanitation workers died of suffocation while cleaning the sewage treatment plant (STP) in the residential township of Guru Gobind Singh Refinery near Talwandi Sabo in Bathinda district on Tuesday afternoon, police said.

The refinery's spokesperson identified the deceased as Astar Ali, Sukhpal Singh, and Rajwinder Singh.

Another worker, Krishan Kumar, who fell unconscious while cleaning the STP, is under treatment at the All India Institute of Medical Sciences (AIIMS), Bathinda.

The victims were around 30 years.

Officials said that four workers were trapped inside the STP after inhaling methane gas.

Rescue teams from the refinery were pressed into service.

Talwandi Sabo sub-divisional magistrate (SDM) Pankaj Kum...