COIMBATORE: Three contract workers died after inhaling toxic gas while cleaning a sewage treatment tank at Tata Electronics Ltd in Krishnagiri on Monday evening.

The deceased were identified as Sarathikumar (25) and Akmal Babu Bhai (28) of Dharmapuri district, and Kaveri (32) of Hosur. They were cleaning the tank when they reportedly lost consciousness and collapsed after inhaling the gas.

Other workers rescued them and rushed them to a private hospital in Hosur. However, all three died on the way to the hospital. Their bodies were sent to the Krishnagiri Government Medical College Hospital for post-mortem examination.

The Rayakottai police rushed to the manufacturing unit and launched an investigation. The incident occurred at the Marigold plant of Tata Electronics Ltd in Vanniyapuram, which employs around 18,000 people from Tamil Nadu and neighbouring States.

Krishnagiri Superintendent of Police GS Anitha visited the unit and conducted an inquiry.

A police officer said a chemical powder was used to prevent foul odour from emanating from the sewage in the nano-filtration feed tank. "We suspect that the chemical may have triggered the release of toxic gas inside the tank," the officer said.

Police are investigating possible lapses in industrial safety procedures, particularly the precautions required before workers enter confined spaces for cleaning. Security has been strengthened at the unit as a precaution.