NEW DELHI — A fast-moving fire ripped through a private hospital in Kolkata on Friday, killing scores of people. Dozens of others were injured from smoke inhalation and patients smashed windows in a desperate struggle to escape. 

The fire broke out in the basement of the Advanced Medical Research Institute, a 161-bed private hospital in Kolkata, the capital of West Bengal, that opened in 1996. A fire official said 73 people had been killed and 100 were injured, but other officials gave slightly lower estimates. 
Witnesses and patients told news reporters that the doctors on duty had abandoned the hospital, leaving patients trapped in their wards at the mercy of billowing black smoke. 
Fire trucks were slow to arrive, witnesses said, and local residents who tried to get inside the hospital to help rescue patients said they were turned away by security guards. 
As a result, many patients were trapped inside and died of smoke inhalation, officials said. 
The blaze is likely to raise fresh questions about safety in India’s booming private hospital business which, like much else in India, is poorly regulated. 
S. Upadhyay, a senior executive at the hospital, said that the facility had smoke detectors and fire extinguishers and conformed to fire safety regulations. 
"I do not know the nature of the fire,” Mr. Upadhyay told reporters. “We're inquiring into the incident. All the fire systems were in place."
 
The government of West Bengal swiftly opened a criminal investigation into the fire and senior officials of the company that owns the hospital surrendered to the police for questioning. 
The hospital had recently been named one of the city’s best by The Week, an Indian magazine that ranks hospitals. 
Fire fighters received the first call at 4:10 a.m. and immediately sent trucks. Witnesses said that fire started at around 3 a.m. Sumit Sur, a fire official at the scene, said that it had been brought under control by early afternoon. 
West Bengal’s chief minister, Mamata Banerjee, spoke to relatives of the victims, who gathered outside the hospital to wait for news of those trapped inside. Many sobbed and screamed as patients were brought out of windows and on gurneys. 
Ms. Banerjee pledged a thorough investigation of the fire. 
“We will take appropriate action for this grave crime,” she told news reporters outside the hospital. 
Angry relatives and local residents accused the hospital of illegally storing flammable items. They accused the hospital of responding too slowly to the blaze and said the guards did not allow bystanders to help with the rescue work.  
“We could have saved many more lives if security guards would have allowed us to enter,” an unidentified local resident told television reporters outside the hospital. 
 
Nikhila Gill contributed reporting.