An elderly woman and her grandchild, who suffered burn injuries in a fire following explosion in a building at Paschim Bakalia Dewan Bazar of Chittagong city on Friday, died at Chittagong Medical College and Hospital on early Saturday.

The deceased are Samuda Khatun, 70 and her grandchild Ifti, 17.

Samuda and Ifti, who received almost 100 percent burn injuries, succumbed to their injuries around 1:30am, said sub-inspector Jahirul Islam, in-charge of CMCH police camp.

Shah Md Abdur Rouf, additional deputy commissioner of Chittagong Metropolitan Police, said the fire broke out on the second floor of the six-storey Madrasah Arabia Khayeria Orphanage building in the early hours after something went off with a big bang, leaving three people critically injured.

The injured were taken to the burn unit of Chittagong Medical College Hospital.

Meanwhile, the reason behind the blast could not be known with police suspecting that it might have taken place from accumulated gas.