Two of them were Malaysians while the third worker was a Bangladeshi. They were working for a cleaning contractor.

The Kuala Lumpur Fire and Rescue Department’s operations centre said the incident was reported at 2.40pm and involved six men initially.

They began suffering breathing difficulties and two of them managed to save themselves before the fire and rescue personnel arrived. The other four were trapped inside the sewage tank.

A Hazmat (hazardous materials) team managed to save one of the trapped men and sent him to hospital.

The other three men who died were taken out from the sewage plant by Water Rescue Unit (PPDA) personnel.

The Hazmat team carried out decontamination of the area to ensure the safety of others there.

Meanwhile, Indah Water Konsortium (IWK) Sdn Bhd, in a statement, said it would extend its full cooperation to the authorities probing the incident.

It said IWK would also conduct an internal investigation to identify the cause of the incident.

“IWK extends its condolences to the families of the victims,” it said.

It said the company expressed regret over the incident because every procedure related to the safety and health of the employees had been followed before carrying out any operational tasks.