Six people died after inhaling toxic gas in a septic tank in Tamil Nadu’s Kanchipuram district on Tuesday, reported The New Indian Express. While one of them fell into the tank accidentally, the other five died while trying to save him.

V Krishnamurthy, a shop owner, wanted to clean the septic tank outside his house in Selvaperumal Nagar. But when he opened the lid of the sewage tank, he felt uneasy and called out his sons for help. However, before they could reach, Krishnamurthy fell in the tank.

His sons, Kannan and Karthik, jumped inside the tank to rescue him. A tenant who saw this tried to rescue them also inhaled the gas and fell inside. Then two others also met with the same fate.

Fire personnel recovered all six bodies. “The victims succumbed to inhalation of toxic gas,” Kanchipuram Superintendent of Police Santhosh Hadimani told The Hindu. “We have registered a case of unnatural death.”