FILE - In this Sunday, Sept. 20, 2020, file photo, Tennessee Titans head coach Mike Vrabel watches from the sideline during the first half of an NFL football game against the Jacksonville Jaguars in Nashville, Tenn. Vrabel’s debut as an NFL head coach came in the league’s longest game because of lightning delays, and now he’s guiding the Tennessee Titans through the league’s first COVID-19 outbreak. (AP Photo/Wade Payne, File)

NASHVILLE, Tenn. (AP) — The NFL’s investigation into how Tennessee turned into the league’s first COVID-19 outbreak found “several specific incidents” of the Titans possibly breaking protocols dealing with the coronavirus pandemic, according to a person with knowledge of the probe.

Also, the headmaster of a private school in Nashville confirmed to The Associated Press on Wednesday that several Titans, including quarterback Ryan Tannehill, practiced on its field Sept. 30. That was a day before the NFL first postponed Tennessee’s game with Pittsburgh before rescheduling to Oct. 25.

NFL Commissioner Roger Goodell warned all 32 teams Monday that following league protocols is mandatory and that violations forcing changes in the schedule could lead to forfeiting games.

Tennessee had two more players test positive Wednesday, a person familiar with the the situation said. The Titans placed starting wide receiver Corey Davis on the reserve/COVID-19 list hours later, bringing their total to 22 cases with 20 returned since Sept. 29.

The Titans cannot return to their facility before Saturday at the earliest, needing back-to-back days without a positive test result. They haven’t been on a field since beating the Vikings 31-30 on Sept. 27. The NFL has to decide if they play Buffalo (4-0) as scheduled Sunday, postpone and reschedule or forfeit.

Titans coach Mike Vrabel said Tuesday any discipline would be something for the NFL to discuss.

“I don’t expect anything either way,” Vrabel said.

The Titans were featured with “several specific incidents” during a call Monday with the league’s general managers and coaches, a person with knowledge of the NFL’s investigation said. Another person familiar with the call said photos from the Titans’ cafeteria were shown.

Both spoke to The Associated Press on condition of anonymity because the investigation is ongoing.

The league is attempting to play a full schedule amid the pandemic without teams isolated in a bubble as other sports have done to protect players and staff from the virus. No games were affected through the first three weeks of the season.

Dr. Allen Sills, the NFL’s chief medical officer, told Judy Battista of the NFL Network the league has looked into everything from video inside the Titans’ facility, interviewing everyone involved and even studied seating charts on buses and planes.

Minnesota coach Mike Zimmer said his Vikings went over the new protocols Wednesday for clubs having been been exposed to a team dealing with a COVID-19 outbreak.