A 27-year-old gunman, identified by police as Shane Devon Tamura of Las Vegas, opened fire with an M4-style rifle at about 6:30 p.m. Monday inside 345 Park Avenue, a Midtown Manhattan skyscraper that houses the National Football League’s headquarters as well as offices of Blackstone, KPMG and other firms. New York City officials said Tamura killed four people and wounded at least five others before fatally shooting himself on the 33rd floor. The dead include off-duty NYPD officer Didarul Islam, 36, who was working a security detail in the lobby, and Wesley LePatner, 44, a senior managing director at Blackstone. Two additional civilians were also killed. One victim remains in critical condition, while four others sustained minor injuries while fleeing. Mayor Eric Adams said investigators believe Tamura intended to attack the NFL’s offices but took the wrong bank of elevators and ended up on a floor leased by Rudin Management, the building’s owner. A three-page suicide note found on his body referenced chronic traumatic encephalopathy and blamed the NFL for his perceived brain injury, according to police officials. The shooting is the city’s deadliest in 25 years and has prompted renewed scrutiny of security protocols in high-rise office towers that line Park Avenue, a corridor increasingly populated by global financial institutions. Blackstone closed its New York offices on Tuesday, and the NFL said one of its employees was among the wounded.