Three contract sanitation workers employed by a private firm were found dead after they were deployed to clean a manhole in Dombivli area of Thane district in Maharashtra on Friday, PTI reported. The deceased, identified as Devidas Pajage, Mahadev Jhope and Ghanshyam Kori, reportedly died after they inhaled poisonous gases in the underground chamber.

SB Sawant, Tilak Nagar police station senior inspector, said they will arrest the contractor once they register a First Information Report against him, The Indian Express reported. “Prima facie, we have ascertained that it was negligence on the contractor’s part as he did not provide safety gear to his workers.”

The police are awaiting the results of an autopsy report. “Pajage had gone in before the others,” an police unidentified official said. “But he collapsed and then the others followed. When none of them came back and did not respond to cries from those outside, the contractor, who was present at the spot, stopped other workers from entering the manhole and called the police.”

Officials said that the workers were employed to clean a sewer line in the Dombivli division of Maharashtra Industrial Development Corporation, Hindustan Times reported.

The Kalyan-Dombivli Municipal Corporation fire team said their personnel also experienced suffocation when they went to retrieve the bodies. “There were no safety masks when their bodies were recovered,” said senior fire officer Suresh Shinde.

Deepak Patil, deputy engineer with Maharashtra Industrial Development Corporation in Dombivli, refuted reports that the workers were not provided with safety gear. He said the corporation only hires contractors who supply safety equipment to its workers and that it had initiated an investigation into the matter.

“The labourers were following the safety measures,” Patil told Hindustan Times. “The police have clicked their pictures. I will check with the contractor who had appointed them. After a detailed investigation, we will take action against the contractor if he is found guilty.”

Manual cleaning of sewers and septic tanks without safety equipment is a violation of the Prohibition of Employment as Manual Scavengers and Their Rehabilitation Act, 2013.