Three furniture workers suffered burn injuries after an explosion in a septic tank at a seven-storey building in the capital's Kalabagan area early Wednesday.

The injured were Md Jewel, 20, Md Rana, 22, and Md Parvez, 21, hail from Bangkhali village under Karimganj upazila in Kishoreganj district.

They were rescued and taken to Dhaka Medical Burn and Plastic Surgery Unit at around 12:30am, said its resident physician Dr Harunur Rashid.

Md Rajib, who accompanied the injured to the hospital, said they work a furniture shop in Panthapath and were varnishing furniture on the ground floor of the building when gas accumulated inside the septic tank exploded, leaving them injured.

Dr Harunur Rashid, said Jewel sustained 30 percent burns, Rana 63 percent and Parvez 21 percent. “Due to the extent of the burns, Rana and Jewel have been transferred to the intensive care unit.”