Police said the gunman, a former employee identified as Dr. Henry Bello, opened fire inside Bronx Lebanon Hospital in the early afternoon.
Seven people were shot, one fatally, while others were injured fleeing the gunfire. Authorities say Bello died of a self-inflicted gunshot wound after apparently trying and failing to set himself on fire.
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According to a law enforcement official, the shooter was wearing a lab coat and had the rifle concealed inside it.
Doctors reportedly refused to evacuate and insisted on treated the wounded right inside the hospital, and many other stories of heroism emerged from the tragedy.
One man, Eric Fisher, described the situation inside the hospital as he was locked in a bathroom with his wife, mother-in-law and newborn son.
The newborn, Ethan Reese Fisher, was in an incubator in the bathroom.
The parents had come in for a routine checkup with a pediatrician when the shooting unfolded.
Watch our interviews with witnesses and bystanders in the video players below:
Hospital employee describes scene during shooting
Hospital employee talks about security protocol at the Bronx hospital
Man spoke with fiancee via phone during Bronx hospital shooting
EMT employee heard gunshots while assisting patient
Hospital employee was on break at the time
Witnesses describe Bronx hospital shooting
Relative of hospital patient discusses Bronx shooting