The deceased was identified as K Ravi from Salem. He entered a 10-foot-deep pit allegedly without any safety gears as part of the works on the second phase of the metro rail project.
According to the police, the co-workers rescued Ravi and gave him water to drink but since he had breathing difficulties, he was immediately taken to a local hospital and declared dead on arrival there.
A case in connection with the incident was registered at the Madipakkam police station.
An official from the station told indianexpress.com that three people, including the labour contractor Bojan, sewage contactor Govindaraj and site engineer Mohan, were booked under Indian Penal Code (IPC) section 304 A (causing death due to negligence).