Doctor Killed in New York Hospital Wasn't Scheduled to Work on Day of Shooting

Dr. Tracy Tam was covering another doctor's shift when she was gunned down by a former hospital employee identified as Dr. Henry Bello.

New details have emerging in the horrifying assault on a New York City hospital ward that left one doctor dead at the hands of a disgruntled former employee and multiple people injured.

Dr. Tracy Tam was gunned down Friday when Dr. Henry Bello, an ex-employee of Bronx Lebanon hospital, hid an AR-15 style rifle under a lab coat and stormed the 16th floor.

Read: Dad Dies Shielding Son From Gunman in Targeted Shooting That Killed 2 Children

In a sick twist to this story of a sanctuary turned deadly, officials have revealed that Dr. Tam wasn't even supposed to be at work at the time of her murder.

The 32-year-old Queens native was covering another doctor’s shift when she was killed, WCBS reports.

A loved one addressed the senseless slaying in a GoFundMe created to help pay for Tam's funeral. 

"She worked extra hours without incentive just to hold hands of patients that are about to pass or just to talk to them and listen to their needs," the page reads. "Tracy Tam was an exceptional, and an extremely compassionate physician. She touched lives of many."

Of the six victims injured, one was a patient and the other five were either doctors or medical students.

The most critical victim was transferred to Mt. Sinai Medical Center for surgery. By Sunday morning, hospital officials told reporters they were happy with the conditions of several of the victims.

"Three have been downgraded to stable, and doing quite well. We are happy with their condition,” the hospital official said. “One particular patient is still critical."

In the aftermath, a picture of Bello is being pieced together from former co-workers who recall his uneven temperament.

"There are many, many details that we're still putting together," Mayor Bill de Blasio said at a Friday press conference. "This was a horrible situation unfolding in a place that people associated with care and comfort, a situation that came out of nowhere."

In fact, it had been two years since Bello was let go and authorities aren't yet sure why he only snapped now and whether or not he was on a mission to kill someone specific when he entered the 16th floor.

What authorities do know is that Bello had a bizarre criminal history and, according to some who knew him, a difficult personality.

"We fired him because he was kind of crazy," Dr. Maureen Kwankam told the New York Daily News. "He promised to come back and kill us then."

More specifically, Bello was reportedly forced out amid sexual harassment allegations.

Bello also had a history of other, unrelated, aggressive behavior, according to The Associated Press. In 2004, he pleaded guilty to unlawful imprisonment after a 23-year-old woman told police Bello picked up and carried her off, saying, "You're coming with me."

He was arrested again in 2009 on a charge of unlawful surveillance after two different women told police he tried to look up their skirts with a mirror.

Bello's unhinged behavior reached a crescendo Friday when, the dead and injured in his wake, cops say he may have doused himself in accelerant and attempted to set himself on fire before sprinklers put out the flames.

Bello then subsequentLy shot himself and collapsed in a hospital hallway, where he died with the rifle at his side, officials said.

Read: 6 Dead, Including Gunman, After Disgruntled Employee Opens Fire in Office: Cops

Bello’s body was near that of the female victim, later identified as Tam, according to NYPD Commissioner James O’Neill.

Officials have not released the identity of other victims.

Watch: Teens Orphaned After Father's Death in Orlando Workplace Shooting