A tragic incident occurred in Haldwani's Gaulapar area on Tuesday evening when a 65-year-old woman and her two sons died of suspected asphyxiation after entering a newly constructed underground water tank.The incident began when 46-year-old Dharmendra Bisht entered the tank to dismantle its shuttering using a ladder.When he did not return, his younger brother Khushal Singh (40) entered the tank to rescue him but also lost consciousness.Their mother, Sarswati Devi (65), then entered the tank to check on her sons and fell unconscious.A farmer, Bhoj Ram, attempted to rescue them but also lost consciousness.Villagers arrived, broke the tank's concrete cover, and pulled out all four.Bhoj Ram regained consciousness, while the three others were declared dead on arrival at Sushila Tiwari Hospital.Police stated the exact cause of death will be confirmed via postmortem.The incident highlights the dangers of unsecured water tanks and the risks of rescue attempts without proper safety measures.Authorities are investigating the circumstances, emphasizing the need for caution in such situations.