Hyderabad, Aug 14 (PTI): Four persons including three sanitary workers were today found dead in a manhole in Ayyappa society in Madhapur area here with the civic officials suspecting that the toxic gases caused their deaths.

An employee of 108 Ambulance service, who tried to rescue them fell ill after inhaling the poisonous gas, said R Kalinga Rao, Madhapur Police Inspector.

"The workers were cleaning the manhole. As three of them did not come out after entering, a local resident named Srinivas also climbed down to rescue them but he too did not come out," the police official said.

All four were found dead inside the manhole and their bodies were sent for post-mortem, Rao added.

A Greater Hyderabad Municipal Corporation official said these four persons might have died due to inhaling poisonous gases.

Deputy Mayor Fasiuddin and civic body officials rushed to the spot.

The 108 employee was rushed to hospital, Kalinga Rao said adding police are yet to register a case in this regard.