After their respective Sunday games had ended, three NFL teams found they had an even more imposing opponent left to face: Uncle Sam.

DEA agents made surprise appearanes with the San Francisco 49ers', Tampa Bay Buccaneers', and Seattle Seahawks' medical staffs. The spot-checks are part of an ongoing investigation tied to a lawsuit by former NFLers, contending that teams mishandled players' drug prescriptions. No arrests were made and none of the three teams seemed to indicate any evidence of wrongdoing.

"Our teams cooperated with the DEA today and we have no information to indicate that irregularities were found," NFL spokesman Brian McCarthy said in an email. Other teams are expected to be similarly investigated in the coming days.

"This is an unprecedented raid on a professional sports league," said Steve Silverman, one of the attorneys for the former players. "I trust the evidence reviewed and validated leading up to this action was substantial and compelling."

The corresponding lawsuit includes over 1,200 former NFL players, some of whom played as recently as 2012. It alleges that NFL teams and their medical staffs did not act in the best interest of their players' health. Staffs reportedly withheld information about injuries while also handing out "cocktails" of prescription drugs "like candy at Halloween." The NFL league office has made a motion to dismiss the lawsuit, maintaining that it cannot be held responsible for the individual conduct of its 32 teams.

A full account of the DEA's "unprecedented" raid, as well as the backstory surrounding this high-profile lawsuit, is available via the Associated Press.