The fire was allegedly started by a short circuit in a ventilator, and 150 people were evacuated from St George City Hospital earlier this morning.
“The fans are at their limit. According to preliminary data, there was an overload and the machine ignited, which caused the fire, “said a source at Interfax News Agency.
The five victims were said to have been connected to fans at the time.
Smoke was seen pouring out of the hospital window which had been reclassified to deal with patients with coronavirus during the pandemic.
The fire would have destroyed 108 square feet inside the building.
Eleven people in the same room on the sixth floor were rescued and taken to the lower floor of the hospital.
It is still not known how many people were injured in the incident.
Emergency services later said the fire had been located.
It comes after an elderly woman was killed after a fire broke out in a Moscow hospital treating patients infected with coronavirus on Saturday.
An oxygen cylinder supplying a ventilator exploded, causing a major fire that resulted in the evacuation of 295 patients, reports said.
Authorities are investigating the causes of the two fires.
The number of new coronavirus cases in Russia increased by 11,656 on Monday, a record daily increase.
This brings the total official number of cases to 221,344.