HARLEM, Manhattan (WABC) -- Authorities have revealed the cause of a fire on a Harlem movie set that killed a firefighter in March.
Fire Marshals determined that heat from a boiler ventilation pipe ignited nearby combustible materials and caused the fire in the basement of a building on St. Nicholas Avenue.
Firefighter Michael Davidson was trapped and killed. He was posthumously promoted to Lieutenant.
Davidson, who was assigned to the nozzle with the responsibility of operating a hoseline to suppress the fire, became separated from his fellow firefighters as conditions rapidly were deteriorating.
Officials said after a desperate search to locate Davidson, he was found unconcious. He was transported to Harlem Hospital, where he died.
The building was home to the former St. Nick's Jazz Pub, a venerable bar that was closed in 2011.
At the time of the fire, the building was being used to film Edward Norton and Bruce Willis' upcoming film "Motherless Brooklyn."
RELATED: Remembering FDNY firefighter Michael Davidson
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FDNY determines cause of fire that killed firefighter on Harlem movie set