The NFL is recommending enhanced security measures at team and league facilities following a shooting last month at a Manhattan office tower by a gunman authorities say was targeting league headquarters.

The memo, which was sent to all teams on Friday, outlined three recommended changes to security protocols. They will be reviewed at a special league meeting on Aug. 26.

“In moments like these, we are reminded that safety is not a background function. It is foundational,” the memo said.

The enhanced measures recommended include: updated threat assessments at every team and league facility to ensure risks are accurately identified and mitigated; presence of armed officers at team and league facilities whenever players or staff members are present; weapons screening for anyone seeking entry into a team or league facility, including the use of walk-through magnetometers and X-ray scanners for bags, similar to the process for obtaining entry into games.

“The Committee recognizes that these changes will affect day-to-day operations and require an investment of time, coordination, and resources,” the memo said. “However, there is no higher priority than the safety and security of our players, coaches, staff, and everyone who works in and around our facilities.”

Investigators believe Shane Tamura, 27, of Las Vegas, was trying to get to the NFL offices after shooting several people in the building’s lobby, then another in a 33rd-floor office on July 28, before he killed himself, authorities said.

Police said Tamura had a history of mental illness, and a rambling note found on his body suggested that he had a grievance against the NFL over a claim that he suffered from chronic traumatic encephalopathy, a degenerative brain disease that can be diagnosed only by examining the brain after a person dies.

Tamura played high school football in California a decade ago but never in the NFL.