Adams made the announcement during a news conference on Monday, Jan. 10, adding that the situation is an "evolving crisis."
The fire broke out on Sunday, Jan. 9, in an apartment at 333 East 181 St. in the Bronx, the New York City Fire Department reported.
Commissioner Daniel Nigro said patients were taken to seven different hospitals following the fire.
Dozens of people were hospitalized with injuries, as the smoke spread throughout the whole building, FDNY reported.
"Don't forget, there are many people fighting for their lives in the hospital who are transported," he said. "So, [the death toll] could, unfortunately, increase again."
Authorities said the fire was caused by a malfunctioning space heater in an apartment.
"We said this yesterday and we will continue to say this is an unspeakable tragedy," Adams said.
An investigation into the fire is ongoing.
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