The accident happened at Sayed’s house behind Montana Club in ward no. 6 of the municipal area in Satkania.
"A leakage from the family's newly purchased cooking gas cylinder was the reason behind the fire, in which the six got burnt," said municipal panel mayor Saiful Alam Sohel.
Two units of fire fighters were asked into the service and it took them over an hour to douse the flames.
"The injured were rushed to a local hospital," said senior station officer of fire service, Humaun Khan.
Medical officer of Satkania Upazila Health Complex, Abdul Ahad Idris, said, that of the injured, four with 80-90 per cent burns were referred to CMCH.
Assistant sub-inspector at CMCH police outpost, Shilbrata Barua said that the four injured were admitted to the hospital around midnight on Thursday.