The US football league has previously faced legal challenges over its failure to address players’ concussions.

New York City Mayor Eric Adams has said that a gunman who killed five people, including himself, sought out the headquarters of the National Football League (NFL), which he blamed for the brain injuries he suffered from.

Adams said on Tuesday that a note carried by the shooter, identified as 27-year-old Shane Tamura, suggests his target was the NFL.

“The note alluded to that he felt he had CTE [chronic traumatic encephalopathy], a known brain injury for those who participate in contact sports,” Adams told CBS News. “He appeared to have blamed the NFL for his injury.”

But Tamura appears to have arrived at the wrong floor of a New York City office tower and instead opened fire in the offices of a real estate firm, on top of shooting people in the ground-floor lobby.