Four workers died on Sunday after inhaling poisonous gas while cleaning septic tank in separate incidents at Khagrachhari and Jashore districts.

The deceased are Rafiqul Islam and Ramjan Ali, residents of Betchhari in Dighinala upazila of Khagrachhari and Imon Hossain, 18, son of Kutub Uddin and Biplob Hossain, 26, son of Abdur Razzak of Burujbagan village in Sharsha upazila in Jashore

In Khagrachhari, three workers were working to clean a septic tank of an under-construction hatchery at Shanirbhar area in Sadar upazila where at first, Rafiqul got down in the morning.

Then Ramjan also got down at one stage hearing no response from Rafiqul, said the other affected worker Saiful Islam.

At one stage, both fell sick inhaling the poisonous gas of the tank while cleaning it around 11:30 pm.

Later, other workers rushed to the scene and took them to Khagrachhari Sadar Hospital, where duty doctor declared them dead.

It is assumed that the two workers died inhaling poisonous gas from the septic tank, said doctors of the hospital.

Director of Development and Extension of Chittagong Hill Tracts Fisheries Project (deputy secretary) Rahman said he was in a meeting. Being informed, he rushed to the hospital and found them dead.

In Jashore, another two workers were killed and two others were injured while working in a septic tank in Buruzbagan village, said sub-inspector of Sharhsa Police Station.

The injured were admitted to the Navaron Hospital, he said.