The NFL reportedly sent a memo to its 32 teams Friday advising them to enhance security after the deadly shooting at the league's New York City offices July 28, according to ESPN.The memo was reportedly sent by the NFL's chief security officer and general counsel to all team owners and presidents and made three recommendations:CLICK HERE FOR MORE SPORTS COVERAGE ON FOXNEWS.COM"The Committee recognizes that these changes will affect day-to-day operations and require an investment of time, coordination, and resources," the memo said, according to ESPN. "However, there is no higher priority than the safety and the sense of security of our players, coaches, staff, and everyone who works in and around our facilities."In moments like these, we are reminded that safety is not a background function. It is foundational."Four people were killed and a fifth was wounded inside the building that serves as the headquarters for Blackstone and the NFL, according to authorities.NYC SHOOTING: WHAT TO KNOW ABOUT SHANE TAMURA, GUNMAN WHO KILLED 4 INCLUDING NYPD COP IN MIDTOWN MANHATTANThe victims were identified as 36-year-old NYPD Officer Didarul Islam, who was off duty working security in the building; Wesley LePatner, 43, a married mother of two who was shot in the buildings lobby; real estate firm worker Julia Hyman, 27; and security guard Aland Etienne.An employee of the NFL was reportedly "seriously injured."Investigators suspect Shane Tamura, 27, of Las Vegas, was trying to get to the NFL offices aftershooting several peoplein the buildings lobby, then another in a 33rd-floor office Monday, before killing himself, authorities said.Security video shows Tamura entering the lobby at 345 Park Avenue and immediately opening fire, shooting multiple people. He then shot a security guard behind a desk with an M4 assault rifle, Tisch said.Tamura waited for an elevator, allowing a woman to leave unharmed before taking it to the 33rd floor. He proceeded to shoot and kill another person before ultimately taking his own life, police said.Tamura was licensed to carry a concealed weapon in Nevada.Follow Fox News Digitalssports coverage on X, and subscribe tothe Fox News Sports Huddle newsletter.