Staff members at Hospital Sultanah Aminah collapsed from inhaling smoke, while trying to evacuate ventilated patients from the Intensive Care Unit after a fire broke out this morning.

Six patients died in the incident, another patient treated for severe burns while 10 staff members were injured including three who are receiving intensive care.

Their efforts managed to contain fire on that floor from spreading.

"Two of our staff nurses and a student physiotherapist tried our best to evacuate the ventilated patients and in their attempt collapsed from inhaling the thick smoke," Health director-general Noor Hisham Abdullah said, adding they were then rescued.

"Their heroic attempt and bravery to save patience touched my heart deeply, for their high sense of responsibility and caring for others," he said in a Facebook posting.

He said the fire triggered sprinklers and staff tried to control the fire using fire extinguishers, to no avail.

According to Health Minister Dr Subramaniam, eyewitnesses saw the fire start in the treatment room next to the ICU.

"The patients were on ventilation with oxygen, and oxygen is a flammable gas.

"That is probably why the fire spread so rapidly and intensely. In a few seconds, it became uncontrollable," he said at a press conference in Johor Baru today.

He said a window had to be broken to rescue the collapsed staff members.

He said the victims died of severe burns and smoke inhalation, and he had instructed the hospital to assist the victims' families.

The hospital could not say when the last fire drill was conducted.

However, the minister said hospital concessionaires must check for safety risks every year, while the ministry has a task force to run such checks for all 145 public hospitals nationwide.

Upgrades to Hospital Sultanah Aminah, which opened in 1942, are ongoing while another hospital is being built in Pasir Gudang to help with congestion.

"I am probably the saddest fellow that this has happened.

"We will definitely see if we need to do further improvements on our current systems once the investigation is complete and we receive the Fire and Rescue Department's report," he said.

Asked on speculation that the fire was caused by a charging mobile phone, he said even the Fire and Rescue Department has yet to determine the cause.

A total 467 patients were evacuated and transferred to Hospital Sultan Ismail and other wards in Sultanah Aminah Hospital, which the Fire and Rescue Department has deemed safe, he said.

The Sultanah Aminah Hospital also has another ICU which has 27 beds, he said.