As for security, badges and sign-in lists for visitors became standard fare in New York office buildings after the Sept. 11 attacks nearly a quarter-century ago. Many buildings installed turnstiles between guard desks and building elevators. In recent months, some buildings had stepped up their precautions even more because of the war in Gaza.

Four people were killed in a shooting Monday evening inside a New York City office building. The gunman, who used a high-powered rifle to open fire in the Midtown Manhattan skyscraper, later died of a self-inflicted gunshot wound,