Three workers died of asphyxiation on Saturday while working inside an illegal coal mine in Gujarat’s Surendranagar district, The Hindu reported, quoting unidentified officials.

The incident occurred after a toxic gas leak in the 100-foot mine near the Bhet village in the Thangadh taluka, according to The Times of India. The workers were identified as Laxman Koli, Viram Koli and Khoda Koli, the newspaper quoted unidentified police officers as saying.

They were declared dead on arrival at a hospital.

Laxman Koli’s father, Savsi Koli, filed a complaint after the workers’ deaths.

A first information report was registered for culpable homicide not amounting to murder and other sections of the Bharatiya Nyaya Sanhita against four persons: Jasa Keraliya, Janak Aniyariya, Khimji Sardiya, and Kalpesh Parmar. They have been accused of failing to provide essential safety equipment to the workers.

While Parmar is a member of the Bharatiya Janata Party and a taluka panchayat member, Sardiya’s wife is the party’s district panchayat member, The Hindu reported. No arrests have been made in the case so far.

The accused persons did not provide essential safety gear to the workers, according to the first information report. It added that the four men who died were working in the mine for the past 15 days.

It also claimed that the accused persons continued to use the mine and sell the coal even though the government had closed it down, The Times of India reported.

This was the fourth such case this year.

“We had launched a special movement against such mining operations and as many as 2,100 such mines were closed and mining wells were completely buried,” The Hindu quoted Surendranagar District Collector KC Sampat as saying.

However, it seems that a few of them have reopened, he added. “Our main concern is the unscientific method that is used for mining,” said Sampat.

Congress leader Manish Doshi noted the frequent incidents of deaths in the district “where illegal mining of coal is rampant with involvement of local politicians of the ruling party [BJP]”, The Hindu reported.

The Aam Aam Party claimed that around 20 persons had died due to similar incidents in the past six months. But only a few incidents were reported in the media, the party alleged.

“There has been hardly any action taken by the government to stop this activity,” party leader Vikram Dave said.