Toxic gases in a 10-foot-deep septic tank allegedly claimed three lives in Murshidabad’s Madartola on Monday morning.

The deceased are Rajab Sheikh, 35, Mahidul Sheikh, 32 and Manirul Islam, 34.

Another worker Ruhul Amin, 30, who fell ill on inhaling the toxic gas, is admitted to Murshidabad Medical College, Behrampore.

The four workers went into the underconstruction septic tank at the residence of Madartold resident Arselim Sheikh on his bidding around 7am on Monday.

The septic tank had been sealed with concrete slabs around three months ago and the workers had gone in to complete the plaster on the inner side.

Eyewitnesses said Rajab was the first to enter the tank. Within a minute of his going down, Mahidul and Manirul heard cries for help. The duo immediately jumped into the tank to rescue Rajab. They, like Rajab, couldn't come up.

Sensing danger, Ruhul asked for help from villagers and then went down with the assistance of a rope. Once inside, he too cried for help and was instantly pulled out by the villagers with the help of the rope.

All four youths were rushed to the hospital.

The doctor on duty declared Rajab, Mahidul and Manirul dead on arrival.

Ruhul was admitted for treatment.

The incident was reported to Hariharpara police station. Cops brought an excavator to demolish the septic tank. They also deployed fans at the accident site to escape harm from the toxic gas.

Superintendent of police Suryapratap Yadav said: “The incident has claimed three lives at Madartola under Hariharpara police station. Probe is on. A case has been started by the police.”

The incident has left the entire village in a state of shock and mourning.

Arselim, who had hired the workers for the completion of the septic tank at his residence, said: “This tragedy has left me in utter shock. Those who died were my neighbours and it cannot get more tragic than this."