The NBA has warned players to protect valuables against “well-organized, sophisticated” transnational criminal networks, according to a memo obtained by NBC News on Friday that echoes a similar warning. issued earlier this week by the NFL.

Security officials at two of the world’s most prominent professional sports leagues are on edge following a series of brazen home burglaries that have targeted some of their sports’ most famous players.

Leon Newsome, the NBA’s senior vice president and chief security officer, told league presidents and general managers that league officials had been tipped off by FBI agents, who warned that “professional athletes and other high net worth individuals” were being increasingly affected by “South American Transnational Theft Groups (“SATGs”)”.

“These SATGs appear to be sophisticated, well-organized rings that incorporate advanced techniques and technologies, including pre-surveillance, drones and signal jamming devices,” according to Newsome.

“SATGs primarily focus on cash and items that can be resold on the black market, such as jewellery, watches and luxury handbags. The FBI reported that in most of the incidents, the homes were equipped with alarm systems that were not. The FBI also reported that all the homes were unoccupied and, in most cases, unoccupied.

The NBA memo did not name any victims.

But the missive was sent this week, following his recent break-ins Milwaukee Bucks forward Bobby PortisMinnesota Timberwolves guard Mike Conley Jr. and Kansas City Chiefs teammates Patrick Mahomes and Travis Kelce.

Earlier this week, the NFL told players to be careful about publicly sharing any information about their whereabouts, homes and luxury items they may own.

“The homes of professional athletes in several sports leagues have become increasingly targeted for burglaries by organized and skilled groups,” the NFL said in the memo.

“It is important that players maintain situational awareness, practice social media safety and implement home security measures to reduce the risk of becoming a target.”

This article was originally published on NBCNews.com