The New York City Fire Department, officially the Fire Department of the City of New York, later determined that the fire was caused by a lithium-ion battery.

" Per #FDNY Fire Marshals, this morning’s 3-alarm fire at 80 Madison Street in Manhattan, which killed four people, was accidental. Caused by a lithium-ion battery on the first floor," the department tweeted.

The department also shared an image of the spot where the fire had broken out.