The gunman who killed four people in New York City was targeting the National Football League.

In a note found in his wallet, the 27-year-old shooter accused the NFL of concealing the dangers of the sport on players’ brains.

Police say the gunman travelled across the country before opening fire in a midtown Manhattan office building.

According to New York Mayor Eric Adams, the gunman who played football in high school was trying to target the NFL headquarters, but took the wrong elevator.

Investigators say he had a history of mental illness.