KRISHNAGIRI: Three contract workers died after drowning while carrying out maintenance and cleaning work inside a nano-filtration feed tank at Tata Marigold Company in Vanniyapuram, in Krishnagiri district on Monday evening.The deceased have been identified as Kaveri, 28, J Akmal, 28, and Sarath Kumar, 25, all from Rayakottai. All three were said to have been undertaking cleaning operations inside the tank when the incident occurred.“They were immediately rescued and rushed to a nearby hospital. However, doctors declared them brought dead,” said C Dinesh Kumar, Krishnagiri district collector.Meanwhile, authorities have launched an inquiry to ascertain the exact circumstances that led to the incident and to determine whether there were any lapses in industrial safety protocols at the facility.The district administration and police are also closely monitoring the situation in and around the industrial unit to ensure that law and order is maintained.Rayakottai police have registered a case and initiated an inquiry.