Hyderabad, Nov 28 : Two labourers were suffocated to death and two others taken ill while cleaning a septic tank in Hyderabad on Sunday, police said. The incident occurred at Gautami Enclave in the Kondapur area. Police said the labourers were cleaning the septic tank in an apartment building when they fell unconscious and died. Two labourers first entered the septic tank but came out after complaining of suffocation. Later, two others went in and after sometime both fell unconscious and died due to inhaling poisonous gas. Fire services and police personnel pulled out the bodies and shifted them to a hospital for autopsy. The deceased were identified as Anjaiah and Srinu. They were residents of Singareni Colony at Champapet in Hyderabad and were native of Nalgonda district. Two other labourers, who took ill, were admitted to a hospital. Police registered a case and took up investigation. A fire services officer said the workers were not wearing any safety gear and this led to the tragedy. Family members of the deceased rushed to the scene and staged a protest, demanding justice. Apartment owners had online contacted a contractor to clean the septic tank due to overflowing of drainage. A tanker was deployed for cleaning, but since the work was not completed, the contractor sent the labourers in to clear the obstruction. /IANS