A tragic blast happened at Manalurpettai in Kallakurichi district on Monday night. A helium gas cylinder used to fill balloons exploded around 7:30 p.m. during the annual River Festival, which marks the end of Pongal celebrations. The explosion killed 50-year-old Kala. Her legs were severed in the blast, and she was declared dead on arrival at Tiruvannamalai Government Medical College and Hospital. At least 12 others were injured and rushed to the hospital. Some victims were found lying on the road and shifted immediately. District Superintendent of Police S. Aravind said six of the injured are in intensive care. Collector M.S. Prasanth confirmed the death and said a boy and the cylinder operator are in critical condition. Officials are probing how the cylinder exploded. The festival venue was crowded as many people had come to celebrate the five-day Pongal festival's finale.