A contractor, Alimuddin Sheikh, was arrested on Monday in connection with the deaths of three wage laborers at the Kolkata Leather Complex on Sunday.

The laborers, Suman Sardar, Farzam Sheikh, and Sheikh Hashibur, from Nazhat in Murshidabad, were allegedly hired by Sheikh to clean an underground sewage line. The incident occurred when one worker fell ill after entering a 10-foot-deep manhole, and the other two went in to rescue him. Rescue workers in diving gear recovered the bodies.

Kolkata Mayor Firhad Hakim visited the site on Sunday and ordered an inquiry, leading to a case being registered at the Bantala police station.

He claimed that the deaths were likely caused by chemical waste from tanneries flowing through the drainage line, which “should have been directed to the effluent treatment plant”. Hakim said that the police investigation would focus on why the men were sent into the manhole without pumps.

The Kolkata Metropolitan Development Authority (KMDA) said it is also conducting an internal investigation.