Four contract workers engaged in maintenance work at a Coal Chemical department of Rourkela’s SAIL steel plant died on Wednesday morning following leakage of toxic carbon monoxide gas, said police officials.

The incident took place around 7:30 am, said Rourkela SP Mukesh Kumar Bhamoo. The officer added it was not yet known how the gas leak occurred.

Dipak Chattaraj, CEO of the RSP, has assured all help to the families of the deceased workers. A high-level probe has been ordered into the incident.

The four who turned unconscious were admitted to the Intensive Care Unit of Ispat General Hospital in Rourkela, but later succumbed to the poisonous gas. The deceased have been identified as Ganesh Chandra Paila (59), Abhimanyu Sahu (33), Rabindra Sahu (59) and Brahmananda Panda (51).

Archana Satpathy, public relations officer of the Rourkela Steel Plant, said all the four worked for a maintenance contractor firm Star Construction. Though there were reports of several other workers being affected by the gas leak, the steel plant spokesperson said only four workers were present at the accident site.

Officials said the coal chemical department in the plant produces coke oven gas that is generated from the Coke Oven Battery. Local officials said a probe would be started as to how the leak happened and the lack of safety protocols at the worksite.

The first integrated steel plant in the public sector in India, RSP produces 4.5 MTPA (Million Tonne per Annum) of hot metal. SAIL proposes to ramp up the hot metal production to 8.8 MTPA by 2030.