The doctor and two nurses who were on duty at the isolation unit for coronavirus patients at United Hospital fled from the scene soon after the fire broke out, handing over the responsibility of patients' lives to a cleaner.

A three-member police team lead by Abdul Ahad, additional deputy commissioner of Gulshan Division of Dhaka Metropolitan Police, disclosed the findings today.

There were two parts in the isolation unit -- one for patients and one for doctors and nurses -- and the fire spread from an air-conditioner in the doctor's room, they further said.

When the fire broke out, the duty doctor left immediately and he was soon followed by the two nurses, who took no steps to shift the patients elsewhere.

A cleaner, Md Arafat, first tried to extinguish the fire using his broom. This, however, did not work and the fire began to spread.

Arafat tried to battle the flames with water, but by then smoke had engulfed the entire room, the police investigation team said.

The team, that was formed to investigate the fire at the hospital on May 27 which killed five patients, already submitted the investigation report to the commissioner of DMP on Wednesday, Sudip Chakrabarty, deputy commissioner of Gulshan Division police, told The Daily Star today.

The report would be sent to Police Headquarters (PHQ) soon, he said.

Regarding the findings, DC Sudip said that the hospital authority built the extension unit for coronavirus patients without taking permission from the authorities concerned. The unit had no measures for fire safety and was built in violation of the Bangladesh National Building Code, he said.

A high official of Gulshan Police, who was closely involved with the investigation, told this newspaper that they are suspecting the patients died from suffocation as the rooms were filled with toxic gas soon after fire broke out from the AC. Then they might have been burnt by the fire, he added.

As the patients already had breathing problems, they died soon after smoke had filled the room, the official said.

Police investigation sources further said that the isolation unit was supposed to be built with non-flammable material, but the hospital authority used flammable ones for the unit.

Regarding the role in stopping the fire, DC Sudip Chakrabarty said none except the cleaner Arafat came forward.

"We saw in the CCTV footage that the lower portion of the AC had fallen on a bed and Arafat was the only person [apart from patients] present inside the unit. Arafat tried to remove the AC's burning part with his broom but it too caught fire," he said.

He also added that Arafat tried to fight the fire for as long as he could, adding the cleaner should be awarded for his bravery.

The DC further said that the other hospital staffers tried to stop the blaze with expired fire extinguishers but to no avail.

Five victims who died in the tragic fire were Vernon Anthony Paul, 75; Riyajul Alam, 45; Khodeja Begum, 70; Md Monir Hossain, 75; and Md Mahabub, 50.

Of them, Vernon Paul and Khodeja Begum's blood samples tested negative for coronavirus and they were meant to be moved to another section of the hospital.