Dwellers of a nearby slum who first noticed the smoke and fire rushed to the AMRI Hospital to raise the alarm, but security guards kept them back, saying it was only a small blaze, witnesses said.
It took firefighters in the city formerly known as Calcutta more than an hour to respond, said Pradeep Sarkar, a witness whose uncle was hospitalized but was among those safely evacuated from the private facility. Some of the slum dwellers helped with the rescue.
The neighborhood's narrow streets apparently made it difficult for fire trucks to get close to the building and to bring in big hydraulic ladders. Eventually, they smashed through a main gate to make way for the ladders.
Six hospital directors surrendered to police and were charged with culpable homicide, according to police who spoke on condition of anonymity because they were not authorized to talk to the media.
Mamata Banerjee, chief minister of the state of West Bengal, ordered the hospital's license withdrawn. The hospital denied that any safety measures were violated.
"It was horrifying that the hospital authorities did not make any effort to rescue trapped patients," said Subrata Mukherjee, West Bengal state minister for public health engineering. "Senior hospital authorities ran away after the fire broke out."
Rescuers pulled 73 bodies from the building and another 16 died of their injuries later, said Danayati Sen, a top Kolkata police official. Most of the deaths were due to smoke inhalation, rescue officials said.
Four of the dead were staff members, hospital officials said.
There were 160 patients in the 190-bed facility at the time, said Satyabrata Upadhyay, a senior vice president.
One survivor told Indian television she was at the bedside of her mother, who was on a ventilator, when smoke started filling the room.
"I kept ringing the bell for the nurse, but no one came," she said, adding that rescuers managed to evacuate her mother more than two hours after the fire started.
Rescue workers on long ladders smashed windows in the upper floors to get to trapped patients before they suffocated from the smoke as sobbing relatives waited on the street. Patients were removed on stretchers and in wheelchairs to a nearby hospital.
Patients and relatives complained that hospital staff did little to help and that smoke detectors failed to go off.
S. Chakraborty said his wife, Moon Moon, who was hospitalized with a broken ankle, had called him at home to say that a fire had broken out. By the time he reached the hospital, she was dead, he said.
Sudipta Nundy said his brother-in-law, Amitabha Das, who was being treated for an infection, died by the time rescuers arrived.
"He would have survived had hospital authorities allowed outsiders in early to evacuate the patients," he said.
Banerjee said that while the fire brigade was delayed, police arrived quickly to help with the rescue.
Not all patients said they were abandoned. Jyoti Chaudhary, in his late 60s, said a hospital worker helped him down a stairway.
The loss of life was "extremely unfortunate and painful," Upadhyay said, adding that the facility followed strict fire safety measures. He promised to give 200,000 rupees, (about $4,000) to the relatives of the dead.
"We deeply sympathize and share the pain and agony of the family members of the patients admitted here," he said.
The expensive AMRI Hospital was recently rated one of the best in the city by an Indian magazine.
However, safety regulations are routinely ignored at hospitals throughout India, where it is common for fire extinguishers, if present at all, to be several years old and never serviced. Few buildings have fire stairways, and drills are virtually unheard of.
The blaze erupted about 3:30 a.m. in the basement and heavy smoke quickly engulfed the hospital. The cause was not immediately known. The basement was being used for storage.
By midmorning, the fire was under control and most of the patients had been moved to other hospitals, said Javed Khan, the state fire services minister.