NEW YORK • A disgruntled doctor armed with an AR-15 rifle went on a rampage on Friday (US time) in the Bronx hospital where he had worked, killing a doctor and wounding six other people - five of them seriously - before setting himself on fire and shooting himself in the head, the authorities said.

The furious attack by the doctor - identified by police as Henry Bello, 45 - sent staff at the Bronx-Lebanon Hospital Centre diving behind desks and doors as gunshots and smoke filled the hallways. Witnesses described medical workers ripping a fire hose from the wall to use as a tourniquet on one victim's leg, while others recalled the horrific sight of the gunman, his torso aflame, running down a hallway.

Bello had a troubled past, having worked at the hospital for about six months before quitting after being accused of sexual harassment, officials said.

Years earlier, he was arrested and charged with sexual abuse after assaulting a woman in Manhattan.

"The situation unfolded in the middle of a place that people associate with care and comfort," Mayor Bill de Blasio told reporters outside the hospital.

The gunman acted alone, Mr de Blasio said, adding that it appeared to be a workplace dispute that ended when the shooter committed suicide - "but not before having done horrible damage", the mayor said.

Police did not identify the person who was killed by the gunman, other than saying she was a doctor. The five seriously injured patients were "fighting for their lives", said police commissioner James O'Neill. The sixth had a gunshot wound in the leg.

Bello was hired in August 2014, according to Mr Errol Schneer, the hospital's vice-president, and he left in February 2015, in lieu of his services being terminated.

Police said he resigned after an accusation of workplace sexual harassment.

In 2004, Bello was arrested and charged with sexual abuse and unlawful imprisonment after a 23-year-old woman told officers he had grabbed her crotch area outside a building in Manhattan and tried to sexually assault her.

The woman told officers that Bello had lifted her in the air and dragged her while saying, "You're coming with me."

Court records indicate that Bello pleaded guilty to unlawful imprisonment in the second degree, a misdemeanour, and was sentenced to community service. The felony sexual abuse charge was dismissed.

Mr Schneer said the hospital did not know about Bello's criminal past when he was hired.

Bello was a graduate of Ross University School of Medicine on the Caribbean island of Dominica, a New York state official said.

The state's Education Department said Bello had received a limited permit to practise as an international medical graduate to gain experience so he could be licensed.

The shooting took place around 2.50pm on Friday (Saturday, Singapore time) on the 16th and 17th floors of one of the Bronx's largest hospitals, which has 1.1 million patient visits and more than 140,000 emergency room visits a year, according to its website.

Dr Sridhar Chilimuri, the physician-in-chief at the hospital, said the doctor who was killed had been shot in the chest.

Of the five victims in serious condition, one is a family service physician, three are medical students and one is a gastrointestinal specialist.

Mr Miguel Mercado, 61, was lying in a hospital bed on the 10th floor, waiting for an MRI scan after complications from back surgery, when police burst into the room and ordered patients who could walk to head down the stairs with their hands up.

"The cops came and started emptying out the rooms floor by floor - 'Everybody get out, get out, get out!'" he recalled an hour after the shooting, standing in the carpark outside the hospital, intravenous tubes dangling from his arm.

"It's been happening almost anywhere, but nobody was waiting for this," Mr Mercado said. "Who would have thought it would happen in a hospital?"

In a separate shooting, 17 people were wounded in a nightclub shoot-out in the southern US state of Arkansas, police said yesterday.

Some of the victims might also have been trampled when gunfire rang out inside the Power Ultra Lounge in downtown Little Rock, local news outlet KATV reported.

"We do not believe this incident was an active shooter or terror-related incident," the Little Rock police department wrote on Twitter.

"It appears to have been a dispute at a concert."

NYTIMES, AGENCE FRANCE-PRESSE