NEW YORK -- Officials have identified the female doctor killed in the shooting rampage at Bronx-Lebanon Hospital Center Friday afternoon, CBS New York reports.

The physician has been identified as 32-year-old Tracy Sin-Yee Tam, of Jamaica, Queens. She had been working at the hospital for nearly a year and was very "well-liked by the hospital staff," said Errol C. Schneer, the hospital's vice president.

Hospital officials said Saturday that Tam normally worked in one of the hospital's satellite clinics and was covering a shift in the main hospital as a favor to someone else.

Only one of the six others wounded in the shooting remained in critical condition Saturday.

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Schneer said the improvement of the five others now listed in stable condition is a testament to how "heroically" staff responded to save lives when a physician forced to resign returned with an AM-15 assault rifle tucked under his white lab coat and opened fire in his old department, killing Tam.

Tracy Sin-Yee Tam Facebook

Dr. Henry Bello then shot himself, and staggered, bleeding, into a hallway where he collapsed and died with the rifle at his side, officials said. A photo showed the doctor on a blood-spattered floor as police stood over him.

"Many of our staff risked their own lives to save patients," Schneer told reporters Saturday at the hospital where the 16th and 17th floors remained closed.

Three patients who were listed as very critical have been changed to stable. A fourth patient remains in stable condition, while a fifth in stable condition is being transferred to another hospital for specialized surgery, Schneer said.

A physician remains in critical condition, Schneer said.

It was unclear if Bello was shooting randomly or aiming at specific staff when he went to the 16th floor and started shooting, two years after he was forced out of the department where he had worked as a family medicine physician.

The Daily News reported Saturday that it had received an email purportedly from Bello about two hours before the rampage.

"This hospital terminated my road to a licensure to practice medicine," the email said. "First, I was told it was because I always kept to myself. Then it was because of an altercation with a nurse."

He also blamed a doctor for blocking his chances at getting a chance to practice medicine.

His former co-workers described a man who was aggressive, loud and threatening. After he was forced to resign amid sexual harassment allegations, Bello told colleagues he would be back to kill them.

"All the time he was a problem," said Dr. David Lazala, who trained Bello as a family medicine doctor. When Bello was forced out in 2015, he sent Lazala an email blaming him for the dismissal.

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

People described a chaotic scene as gunfire erupted, spreading terror throughout the medical facility as employees locked themselves inside rooms and patients feared for their lives after hearing an announcement warning of someone in the building with a weapon.

According to New York State Education Department records, Bello graduated from Ross University and had a limited permit to practice as an international medical graduate to gain experience in order to be licensed. The permit was issued on July 1, 2014, and expired last year on the same day. Family medicine doctors handle more routine cases, such as coughs and sprained ankles.

Bello also worked as a pharmacy technician at Metropolitan hospital in Manhattan because he was having a hard time getting licensed as a physician, but quit the job in 2012 and filed for unemployment, according to the lawyer who represented him on appeal in 2014. He lost his case. One former colleague at Metropolitan said he would frequently argue with nurses and bristled at being told what to do, but his attorney in the unemployment action said that's not the man he knew.

"I'm absolutely shocked," attorney David Wim said. "He was such a nice gentleman. He was very humble, very polite, very respectful."

Police officers with the Forensics Unit leave Bronx Lebanon Hospital after a gunman opened fire and then took his own life there, Friday, June 30, 2017, in New York. Mary Altaffer / AP

Wim said he jokingly suggested to his assistant that she date the doctor, who was unmarried.

But Bello had a history of aggressive behavior. In unrelated cases, the doctor pleaded guilty to unlawful imprisonment, a misdemeanor, in 2004 after a 23-year-old woman told police Bello grabbed her, lifted her 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 reported he was trying to look up their skirts with a mirror. That case was eventually sealed.

It was not immediately clear if the hospital was aware of his criminal history when he was hired.

Medical staff at the hospital immediately treated all the patients in its emergency department. The victims largely suffered gunshot wounds to the head, chest and abdomen.

One was a patient and the five others are medical staff at the hospital, officials said. Two are medical students and the remaining are physicians.

One of the physicians underwent extensive surgeries after suffering gunshot injuries to the hand and is expected to fully recover. Another doctor is recovering after being shot in the neck.

The 120-year-old hospital has one of the busiest emergency rooms in New York City.