A day after a major fire at the ICU of a civil hospital in Maharashtra's Ahmednagar district killed 11 people, it has emerged that some of the victims died due to smoke which engulfed the ward following the blaze, according to a police official.

The blaze erupted around 11 am on Saturday in the Intensive Care Unit (ICU) ward where 17 COVID-19 patients, many of them senior citizens and some on ventilator or oxygen, were undergoing treatment at the hospital in Ahmednagar, located 120 km from Pune and 253 km from Mumbai.

The ward had been added to the hospital after the pandemic began, officials earlier said.

"Some patients died of burns, while some died due to the smoke. We are waiting for a detailed postmortem report. Further investigation in the case is on," Topkhana police station's assistant police inspector Juber Mujawar said on Sunday.

One of the deceased is yet to be identified, he said.

Late Saturday evening, a case was registered against unidentified persons under Indian Penal Code Section 304 (A) (causing death by negligence), Ahmednagar district Superintendent of Police Manoj Patil.

A short circuit was suspected to be the cause of the blaze, though it was yet to be confirmed, chief fire officer of the city civic body Shankar Misal said.

According to the patients' relatives who normally waited in the corridor outside the ICU, they had been asked to step out as cleaning was going on. Many of them rushed back when they saw thick black smoke billowing from the ward and tried to rescue the patients.

As per district Collector Rajendra Bhosale, a fire audit had been carried out at the hospital. But according to Misal, after the audit, the work of installing necessary safety systems was incomplete due to "want of funds".

Most of those who died were aged between 65 and 83, according to hospital officials.

A probe committee headed by Misal will look into what led to the tragedy, the collector earlier said.

Chief Minister Uddhav Thackeray on Saturday said an in-depth probe will be conducted by the district collector, according to a statement issued by the Chief Minister's Office.

Maharashtra Energy Minister Nitin Raut ordered a detailed inquiry into the fire. The electricity department's inspection team had reached the hospital and will conduct a probe, he said.

In April this year, 15 COVID-19 patients had died in a blaze at the ICU of a private hospital in the state's Palghar district.

Another fire in March at Dreams Mall in Mumbai's Bhandup area, which housed a Covid-designated hospital, had claimed the lives of nine such patients.