A 48-year-old worker, Rishi Pal, died while cleaning a sewer tank at the Lok Nayak Hospital in New Delhi on Sunday. Three others fell unconscious after inhaling the toxic gases that killed Pal. This is the tenth such incident in the national Capital in the past 35 days, according to The Times of India.

The police said Pal had entered the manhole, located near the hospital’s Gynaecology Department, first to clear two clogged lines around noon. When he did not immediately come out, two other workers – Bishan and Kiran – followed one after the other. When none of them came out after a few minutes, another worker, Sumit, who was wearing a mask, alerted those nearby and then entered the tank and pulled the others out, before he also fainted, .

Sumit was the only one who received a mask from the hospital, according to The Hindu. He has been discharged from the hospital, but the other two are still in critical condition.

The police have booked the contractor who hired these men for culpable homicide not amounting to murder and attempt to commit culpable homicide. However, he is absconding right now.