10-year old Sandeep, son of one Mukesh, native of Magrasa village under Bidhnu police station, dropped the note in the septic tank this morning, police said.
The tank had a broken lid through which Sandeep entered the 10-ft deep tank with the help of stairs. He immediately fell unconscious after inhaling the poisonous gas inside the tank, police said.
Sensing trouble, Mukesh entered the tank after he heard his son was trapped inside but suffered a similar fate, they said. Neighbours Neeraj and Sadhu rushed to help them but they too fell unconscious after entering the tank.
The incident created a chaos in the village following which police were informed. Police rushed the victims to a hospital where they were declared brought dead.
The bodies have been sent for postmortem, police said, adding that probe has started into the incident.
