The Delhi Police said hat two persons died after they inhaled toxic gases while cleaning a septic tank in Azadpur area of the national Capital, PTI reported on Tuesday. The police received information around 6.45 pm on Sunday about the incident, and sent four fire tankers to the spot for a rescue operation.

“Three of the seven men cleaning the tank fell unconscious,” said Deputy Commissioner of Police (Northwest) Vijayanta Arya. “They were taken to the BJRM Hospital. On reaching the hospital, two of them – Idris, 45, and Salim, 45, – both residents of Khurja in Uttar Pradesh, were declared dead. Abdul Saddam, 35, Salim, 35, and Mansoor, 38, were treated and discharged from the hospital.

The company that owns the factory manufactures gold and silver chains, and stores chemicals used in making ornaments and the water used for washing in a septic tank. Factory owner Rajender Soni gave the tender for cleaning the tank to contractor Pramod Dangi, 35, a resident of Najafgarh, the police said.

A case under relevant provisions of law has been registered and the factory owner and the contractor have been arrested. Arya said the workers were not wearing any safety gear while entering the tank and were paid Rs 400 each to clean the tank.

In August, six men died in an under-construction septic tank in Deoghar district of Jharkhand. “Prima facie, it seems that they died of suffocation due to possible accumulation of lethal gases such as carbon dioxide or monoxide in the septic tank,” Deoghar Deputy Commissioner of Police Kamleshwar Prasad Singh said.

Devipur Circle Officer Sunil Kumar said that when local residents broke open the tank, all six men were found unconscious. “They were immediately rushed to Sadar hospital where they were declared brought dead,” he said.