Fire authorities said a gas leak or a stove could have caused Thursday's blaze in the capital, which spread quickly after breaking out in a biryani restaurant, and was only reined in following two hours of effort by 13 units of firefighters.
Hospitals are treating 22 people with burn wounds, Health Minister Samanta Lal Sen told reporters on Friday.
"All 22 people ... are in critical condition," Sen said after a visit to the Dhaka Medical College Hospital.
Prime Minister Sheikh Hasina expressed shock and sorrow over the incident, ordering officials to provide swift treatment for the injured.
One survivor, Mohammad Altaf, recounted his narrow escape from the blaze that killed two colleagues.
"I went to the kitchen, broke a window and jumped to save myself," he told reporters, adding that a cashier and server who urged people to leave during the first moments had died later.
Firefighters used cranes to rescue people from the charred building, said fire officials, who were still working to clear debris and stamp out any remaining embers.
Relatives gathered at the hospital early on Friday to receive the bodies of the dead, with some mourning outside the emergency department.
Doctors said most of the dead were killed by suffocation with others dying as they jumped off the building, which also houses some clothing and mobile telephone shops.
The fire could have originated from a gas leak or stove, said Brigadier General Main Uddin, a top fire service official.
"It was a dangerous building with gas cylinders on every floor, even on the staircases," he told reporters.
The government has set up a five-member panel to investigate the incident.
Intense scrutiny of Bangladesh and the major global clothing retailers that manufacture there has helped prevent disasters in the garment sector since a fire in 2012 and a building collapse in 2013 together killed more than 1200 workers.
But in other industries, mainly catering to Bangladesh's booming domestic economy and lacking equal emphasis on safety, hundreds of people have died in fires.
In July 2021, many children were among 54 people killed at a food processing factory outside Dhaka, while at least 70 were killed in a February 2019 fire that engulfed a centuries-old precinct.
