Police say a gunman who killed four people in a Manhattan skyscraper before taking his own life claimed to have a brain disease linked to contact sports and was trying to target the National Football

The gunman in the deadly shooting at a New York City office tower had a background in casino surveillance and once held a private security guard license

The Manhattan high-rise shooter, a former high school football player, left a note referencing the brain disease CTE and appeared to have targeted the NFL’s offices, authorities said.