Bronx hospital: Ex-employee gunman 'quit after accusation'
The doctor who attacked his former New York hospital workplace had resigned in 2015 after being accused of sexual harassment, reports said.
Henry Bello had also been convicted of sexual assault a decade earlier, the New York Times reported.
He opened fire with an assault rifle in the Bronx-Lebanon hospital, killing a female doctor and injuring six other people, five of them seriously.
He then shot himself after attempting to set himself on fire, police said.
Some New York newspapers quoted a doctor at the hospital as saying Bello had vowed revenge on his colleagues after he left.
"We fired him because he was kind of crazy," Dr Maureen Kwankam told the New York Daily News newspaper. "He promised to come back and kill us then."
In 2004 Bello was charged with sexual abuse and unlawful imprisonment after a 23-year-old woman said he had grabbed her crotch outside a Manhattan building, the New York Times reported.
Bello walked into the 1,000-bed hospital at about 14:55 local time (18:55 GMT) with an assault rifle hidden inside his white medical coat, reports said.
Mayor Bill de Blasio said the attack had been a "horrific situation in the middle of a place that people associate with care and comfort".
Several of the injured are "fighting for their lives," he said.
The attack began on the 16th floor and all the victims were shot on the 16th and 17th floors.
An assault rifle was also discovered nearby, which a local politician separately said appeared to be a military-grade M16 rifle.
Messages on social media spoke of doctors and nurses barricading themselves inside the building in the Mount Hope district.
One patient in the radiology department, Felix Puno, tweeted: "Building is in complete shut down, I was in the middle of getting an X-ray when security alerted us to the active shooter situation."
Garry Trimble, whose fiancée works at the hospital, said security was not good enough.
He said: "I can walk through the back door with an employee. If the employee opens the door, I can walk in. I think every hospital should have one police officer at each entrance. They only ever do something when something happens."
Bronx-Lebanon is a private, not-for-profit hospital that has been operating for 120 years.
Shootings at hospitals are not common, but there have been several such instances in recent years.
In 2015, a man entered a Boston hospital and asked for a cardiologist by name, shooting him dead when he arrived. During the investigation, it emerged that the man's mother had previously been a patient at the hospital.
In July 2016, another man opened fire in a patient's room at a Florida medical centre, killing an elderly woman and a hospital worker. The suspect was later deemed to suffer from mental health issues, casting doubt over his competency to stand trial.
In July last year, a patient at a Berlin hospital shot a doctor before turning the gun on himself. The city had also seen a shooting outside another hospital earlier in the year, in which no-one was killed.