A gunman who killed four people when he stormed a skyscraper in the heart of New York on Monday evening left a note that appeared to blame the National Football League (NFL) for his brain injury, the city's Mayor Eric Adams has said.
The attacker, 27-year-old Shane Tamura of Las Vegas, shot himself dead after opening fire in the lobby of a building where the American football league has offices.
The gunman was carrying a note in which he blamed CTE, a brain disease triggered by head trauma, on his mental illness, Adams said.
Tamura was a football player during his time at high school in California, ex-teammates have told US media.
New York City police officer Didarul Islam, 36 - who was working as a security guard at the building - was among those killed. Three more victims are yet to be formally identified.
