Chennai, Feb 14 (PTI) Three persons were asphyxiated when they were cleaning the sewage tank at a private food unit at neighbouring Kancheepuram.Chief Minister K Palaniswami said in a statement that the three--Bhagyaraj, Murugan and Arumugan died while cleaning the tank at Katrambakkam in the district, and expressed grief.He said he has asked the district administration to provide Rs 10 lakh each to the families of the victims and has directed that due legal action be taken in the matter.