FDNY Commissioner Daniel Nigro said the fire began in an apartment that spans two floors -- the second and third floor of the building.
"It started in a malfunctioning space heater, that was the cause of the fire. The fire consumed the apartment that is on two floors and part of the hallway," he said.
"The door to that apartment – unfortunately when the residents left – was left open, it did not close by itself. The smoke spread throughout the building, thus the tremendous loss of life and people fighting for their lives right now in hospitals all over the Bronx," Nigro said.
"The marshals have determined through physical evidence and through first-hand accounts through residents that this fire started in a bedroom in a portable electric heater."