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.

A gunman who killed four people at a Manhattan office building was trying to target the headquarters of the National Football League (NFL) but took the wrong lift, according to New York City mayor Eric Adams.

Shane Tamura, the Park Ave. gunman who killed an NYPD officer and three others before taking his own life, left behind a suicide note saying he suffered from CTE, a brain injury often linked to playing football, and was targeting the NFL — but took the wrong elevator, officials said Tuesday.