The NFL is growing concerned about a possible international crime ring targeting its players.

Following the reports from ABC News and Fox 4 Kansas City that a South American crime ring may be connected to the Oct. 6 and 7 burglaries at Travis Kelce‘s and Patrick Mahomes‘ houses in Kansas City, the NFL has issued a memo regarding player security.

PEOPLE obtained a copy of the memo sent by the NFL to its team security directors and the players’ union warning about organized criminals targeting the homes of professional athletes.

The memo sent out by the NFL informed recipients of the perpetrators’ strategy in finding targets and suggested that players utilize increased privacy measures like waiting to post on social media until after they’ve left a location and installing advanced security systems.

A source close to the situation told NFL inside Tom Pelissero that the transnational crime ring is “legit” and been “focused on” NBA and NFL players “over the last three weeks.”

“And it’s all over the country,” the source added.

Travis Kelce, Patrick Mahomes.Getty(2)

As additional information about the suspected crime ring is made public, multiple people close to the situation warned that the perpetrators are using public records to find the addresses of their pro-athlete targets, and “conduct extensive surveillance” before burglarizing the residence.

The memo also said the burglars are “non-confrontational” and do not act while the residents are home. Instead, they track the target’s social media accounts — and those of their families — as well as team schedules to know when the homes will be empty.

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PEOPLE reached out to the NFL for comment, but did not immediately hear back.

Mahomes’ eight-acre Belton, Mo. estate was broken into on Oct. 6. When asked about it during a Chiefs press conference, the quarterback said, “Obviously, it’s frustrating, disappointing but I can’t get into too many of the details because the investigation is still ongoing.”

Patrick Mahomes #15 of the Kansas City Chiefs looks on during the national anthem.Michael Owens/Getty

Mahomes added that it was “something you don’t want to happen to really anybody.”

Kelce’s Leawood. Mo. residence was broken into on Oct. 7, the day the Chiefs played the New Orleans Saints at Arrowhead Stadium, and police said $20,000 was taken from the tight end’s home.

Over in the NBA, Milwaukee Bucks forward Bobby Portis’ home in River Hills, Wis. was also burglarized similarly.

Portis, 29, revealed on Instagram that many of his “prized possessions” were taken from his Milwaukee residence during a Nov. 2 home invasion. The NBA champ said the burglary occurred while he was in Ohio for a road game against the Cleveland Cavaliers.