No casualties were reported from the fire that originated on Thursday evening, but a child patient died during transfer to another hospital.
Fire Service officials suspect electric short circuit caused the fire, but they differ with the hospital authorities about the place of origin.
The firefighters say the fire might have started in a storeroom on the ground floor while hospital officials assert they first spotted it at the paediatric ward on the second floor.
The hospital resumed treating patients to a limited extent when the fire was doused after around three hours of efforts, Medical Education and Family Welfare Secretary GM Saleh Uddin told bdnews24.com.
The patients can now return or continue treatment where they have been admitted, he added.
Five units were sent to the hospital to douse the fire initially, and 11 more joined in later, officials said.
Health Minister Zahid Maleque and State Minister for Health Murad Hasan rushed to the hospital.
“No casualties have been reported. All the patients have been evacuated,” Maleque said.
There were over 1,000 patients in the government hospital, according to officials.
The health ministry in a statement said Health Services Secretary Ashadul Islam also visited the hospital, along with Minister Maleque, State Minister Murad and other top officials.
The minister asked the authorities to transfer the patients to other hospitals and urged all to keep calm and not panic.
He told the media that the authorities were investigating the origin of the fire.
Many panicked patients rushed to safety after seeing smoke billowing into the sky, witnesses said.
A relative told bdnews24.com that he took his patient home on seeing the fire.
Some patients admitted to the Intensive Care Unit were being taken to other hospitals.
Power supplies to the hospital were stopped for around an hour after the fire ensued.
Videos posted on the social media showed smoke billowing from an under-construction part of the hospital.
There were 1,100 to 1,200 patients at the hospital and 10 at the ICU, its Director Uttam Barua told bdnews24.com.
They were later transferred to Dhaka Medical College Hospital and Kurmitola Medical College Hospital, he said.
Some were getting admitted to private hospitals as well.
A one and a half years old child patient died while being transferred to the hospital, according to Abdullah.
The child was given oxygen, but the oxygen mask was removed during the transfer and doctors declared the child dead on arrival, he said.
When the fire was doused, the authorities started checking for its origin and assessing the extent of damage, but no conclusion could be drawn.
Hospital Director Barua believes it had originated from the paediatric ward on the second floor.
An employee also said they first saw fire on the second floor.
But Fire Service DG Khan said the fire originated in a storeroom and spread to 10 to 15 other store rooms on the ground floor while smoke spread to other floors.
The firefighters were checking all the rooms to put out the flames, he added.
The Fire Service DG said the fire also spread to some parts on the other floors.
“It’s the nature of fire to go upwards,” he said.
He, however, admitted that the children’s ward on the second floor suffered most damage.
Its Director General Abul Kalam Azad said an additional secretary was heading the committee consisted of representatives of different related agencies.
One ‘Abdulla’, relative of a patient, said he wanted to douse the fire just after it had started but could not find any fire extinguisher nearby.
“The situation would not have been this worse had I found an extinguisher,” he said.