At least 20 people were feared to have suffocated to death in a massive fire that broke out at the AMRI hospital in Dhakuria of south Kolkata early on Friday, West Bengal Municipal Affairs minister Firhad Hakim said.
"From whatever information I have got from the fire department officials, there is a possibility that at least 20 people may have died," said Hakim, who was at the spot.
News channels are reporting that at least 40 people - patients, nurses and doctors - are still trapped inside the burning building.
The blaze reportedly started at 3:30am Friday morning.
City officials have deployed at least 20 fire engines to the spot but reports claim the narrow road leading up to the hospital is hindering emergency rescue.