Shots were fired inside New York City's Bronx Lebanon hospital on Friday, and police said a short time later that one suspect was dead, while local media reported several people, including at least three doctors, were wounded in the gunfire.
Few details were immediately available about the incident from official sources.
The New York Times, citing information furnished by an unnamed city Fire Department official, reported that three physicians had been shot, though their conditions were unknown.
As least one of the wounded doctors was being treated by people inside the hospital who fashioned a tourniquet from an emergency fire hose, according to the official, the Times said.
As many as five or six people may have been wounded, the Times said, citing a law enforcement official who spoke on condition of anonymity.
Police swarmed the hospital searching for an assailant, the New York Daily News said.
CBS News reported that the gunman, believed to be a former hospital employee, had a rifle and had barricaded himself inside the building.
New York Police Department spokesman Peter Donald posted a message a short time later on Twitter, saying, "One shooter is deceased at the hospital." It was not immediately clear whether police were looking for any other suspects.