At least four workers sustained burn injuries after an empty chemical drum exploded at an under-construction building in the city.
The incident took place in Agargaon area of the city on Monday morning.
The victims were identified.
Injured Rabin, 19, Rafiqul Islam, 24, Sarlal Das, 45, and Mozaffar, 26, were admitted to Sheikh Hasina National Institute of Burn and Plastic Surgery.
The condition of Rafiqul and Rabin is slated to be critical, said resident physician Dr Mohammad Tariqul Islam.
The incident happened at about 9am in Taltola bazar.
Another worker Sarder Shafiqul Islam, who rescued the four injured.
He said an empty chemical drum was brought to the building for keeping water.
Suddenly, it exploded when the workers were cutting the front part of the drum, leaving the four workers burnt.
