The fire broke out at the Al-Hussein hospital in the southern city of Nasiriya late on Monday and was brought under control by civil defense teams.
A medical source with the health directorate told AFP news agency the “main reason behind the fire… was the explosion of oxygen tanks”.
Blaze at Nasiriya hospital’s coronavirus ward is second to hit a COVID unit at an Iraqi hospital in three months, according to Aljazeera.
Health sources told Reuters news agency the death toll could rise as many patients were still missing. Two health workers were among the dead, they said.
Health officials at Nasiriya said search operations at the hospital were continuing, but that thick smoke was making it difficult to enter some of the burnt-out wards.
Footage shared online showed thick clouds of smoke billowing from the hospital buildings.
Al Jazeera’s Mahmoud Abdelwahed, reporting from Baghdad, said family members and city residents had rushed to the scene.
Iraqi Prime Minister Mustafa al-Kadhimi also declared a state of emergency in the governorate of Dhi Qar, where Nasiriya is located, Abdelwahed reported.
In a tweet, al-Kadhimi said that his office was holding an emergency meeting to discuss “the causes and repercussions” of the incident.
Earlier on Monday, a minor fire broke out at the health ministry’s headquarters in Baghdad, but it was quickly contained and no fatalities were recorded.
The blaze at the Nasiriya hospital is the second such tragedy this year.
In April, a fire at a Baghdad COVID-19 hospital sparked by the explosion of badly stored oxygen cylinders killed 82 people and injured 110 others.
Many of the victims were on respirators being treated for COVID-19 and were burned or suffocated in the resulting inferno that spread rapidly through the hospital, where dozens of relatives were visiting patients in the intensive care unit.
The then-health minister, Hassan al-Tamimi, resigned.
Iraq has recorded more than 1.4 million coronavirus cases and more than 17,000 deaths.
MAH/PR