A gunman has opened fire inside a hospital in the Bronx borough of New York, injuring several people, police say.
The man, said to have been dressed as a doctor and armed with a rifle, is now dead, they said.
The shooting began at about 14:45 local time (18:45 GMT) at the 1,000-bed Bronx-Lebanon Hospital.
Police identified the gunman as Henry Bello, a former doctor at the hospital. Reports say he killed himself.
Messages on social media spoke of doctors and nurses barricading themselves inside the building in the Mount Hope district.
The victims were reportedly shot on the 16th and 17th floors.
The New York Police Department posted a tweet urging members of the public to avoid the area around the hospital at 1650 Grand Concourse.
The New York Times quoted a fire department official as saying that three doctors had been shot. Their condition is not known.
Emergency medical workers cannot yet enter the building as it has not yet been secured by police.
The fire official told the Times one injured doctor was being treated by people inside the hospital using a fire hose as a tourniquet.
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.”
Bronx-Lebanon is a private, not-for-profit hospital that has been operating for 120 years.