Story highlights The DEA interviewed doctors and trainers for the San Francisco 49ers

There are reports other teams were questioned, but DEA declined to comment

The investigation stems from a lawsuit alleging illegal handling of prescription drugs

The NFL, already under fire for its handling of concussions and domestic violence, saw several teams visited by the Drug Enforcement Administration after their Sunday games.

It follows yet another allegation that the nation's most popular sports league has less than the highest regard for its players' well-being, as team trainers are being accused of handing out prescription painkillers to keep players on the field.

DEA agents interviewed doctors and trainers of several NFL teams after their games as part of an investigation into allegations of illegal dispensing of prescription drugs.

The DEA questioned the medical and training staffs of the San Francisco 49ers following the team's 16-10 victory at the New York Giants, agency spokesman Rusty Payne told CNN.

The 49ers cooperated with the "random inspection" at MetLife Stadium, the team's director of communications, Bob Lange, said. The team departed the stadium as scheduled, he added.

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The Tampa Bay Buccaneers announced via Twitter that the DEA "checked in" with the team at the Baltimore-Washington International Airport. After a five-minute delay, the team proceeded to its plane without incident, the team said.

A Justice Department official told CNN that DEA agents interviewed team doctors at "several locations."

The DEA investigation stems from allegations in a lawsuit filed by 1,300 former NFL players that the league illegally provided powerful painkillers and other prescription drugs to keep them on the field.

The class-action lawsuit was filed in California in May.

Other allegations include that drugs were being administered by staff -- specifically athletic trainers -- lacking the licenses to do so. If true, these actions would violate the Controlled Substances Act.

Sunday's questioning of doctors and trainers was administrative and not criminal, Payne said. No arrests were made, he said.

"Our teams cooperated with the DEA today, and we have no information to indicate that irregularities were found," said Brian McCarthy, the NFL's vice president of corporate communications.

The players' suit accuses NFL trainers of handing out pills without prescriptions and without regard to possible dangerous interactions with other drugs.

The named players in the lawsuit include former Chicago Bears quarterback Jim McMahon who, according to the lawsuit, says he got hooked on painkillers by taking as many as 100 Percocet pills a month.