Twenty-two patients were at the hospital in the Thane region near the state capital Mumbai, six of them in the intensive care unit, local police officer RB Valatkar said.
The officer added that there were no COVID-19 patients at the facility.
“Four patients in the ICU had died, according to initial investigations, the critical patients may have died because of asphyxiation, and not burns, while they were being rescued,’’ Valatkar said.
He said that the remaining 18 patients were shifted safely to other hospitals.
Police said the fire might have been caused by an electrical short-circuit which gutted one of the floors of the three-storey building.
State authorities ordered a probe to determine cause of the fire and promised strict action if any laxity was found on the part of the hospital management.
Domestic media had attributed the spate of hospital tragedies in Maharashtra to overwhelmed medical facilities working non-stop to treat huge numbers of patients.
On April 23, 13 COVID-19 patients died after a fire erupted at a hospital.
Two days prior, another 24 patients died in a hospital after they lost oxygen supply due to a leak.
In March, 10 patients died in another fire at a COVID-19 hospital. (dpa/NAN)