Four people died in two separate incidents after entering septic tanks in Chattogram city and the district's Raozan upazila on Friday.

In the city, two construction workers died after becoming trapped inside a septic tank while working at an under-construction multi-storey building in Dhaniyalapara under Double Mooring police station.

The deceased were identified as Sakib and Hridoy.

Double Mooring Police Station Officer-in-Charge (OC) Shahinur Alam said the incident occurred around noon at a building under construction near American Building and Lucky Mansion in the Choto Mosque by-lane area of Dhaniyalapara.

The two workers reportedly suffocated after entering the septic tank on the ground floor of the building for maintenance work.

Police and Fire Service personnel recovered the bodies and sent them to the morgue of Chattogram Medical College Hospital for autopsy, the OC said.

In a separate incident in Raozan upazila, two workers died after entering a septic tank to clean it at a house under construction in Jhikuti Para of Noapara union.

The deceased were identified as Pradip Das of Kochukhain area in Raozan and Samiran Das of Kodurkhil area in neighbouring Boalkhali upazila. Pradip was also the son-in-law of the house owner, locally known as Ratan Doctor.

Raozan Police Station Officer-in-Charge (OC) Jasim Uddin confirmed the deaths.

According to local residents, Pradip entered the septic tank around 12:30 pm and became ill after inhaling toxic gas accumulated inside the tank, which had remained closed for a long period.

Samiran entered the tank in an attempt to rescue him but also lost consciousness after being exposed to the gas.

Fire Service personnel later recovered both men and rushed them to a hospital, where doctors declared them dead.