Three men, engaged to clean a huge septic tank at a resort in Sriperumbudur near here, died of asphyxiation on Friday, police said.

The men got exposed to the toxic fumes of the sewer gas when they descended into the septic tank and fell into it, police said. Upon being informed, the fire and rescue service personnel rushed to the spot and retrieved the bodies.

The deceased were identified as Ranganathan (51), Naveen Kumar (30) and Thirumalai (18).

The Sriperumbudur police detained the manager and contractor of the resort which engaged the three men to clean the septic tank.

Further investigation is underway.