AP photo by Jim Mone / The Tennessee Titans, shown as the national anthem plays before their road game against the Minnesota Vikings on Sept. 27, continue to receive positive test results as they deal with the NFL's first COVID-19 outbreak.

Updated with more information at 11:55 p.m. on Oct. 7, 2020.

NASHVILLE, Tenn. (AP) — The NFL's investigation into how the Tennessee Titans became the league's first team with a COVID-19 outbreak found "several specific incidents" of them possibly breaking protocol related to the coronavirus, 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 Week 4 home game against the Pittsburgh Steelers before rescheduling it for Oct. 25.

Commissioner Roger Goodell warned all 32 teams Monday that following the league's protocol 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 situation said. Hours later, the Titans placed starting wide receiver Corey Davis on the COVID-19 reserve list, 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 Minnesota Vikings 31-30 on Sept. 27. The NFL has to decide if they will play the visiting Buffalo Bills (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 noted 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 AP 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 professional sports leagues have done to protect players and staff from the virus. No games were affected through the first three weeks of the NFL 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. Sills also made clear the league expected positive cases all along.

"The exercises are not just about did someone follow the protocols or not, but are there vulnerabilities we can tighten up, what can we learn and where can we get better and how can we improve going forward," Sills said. "And we've already made a number of those changes."

Vikings coach Mike Zimmer said his organization went over the new protocol Wednesday for clubs having been been exposed to a team dealing with a COVID-19 outbreak. Having played Tennessee helps his Vikings understand the significance of following the league's guidelines to stay safe.

"You look at the Pentagon, they've got it. The White House has got it. The NFL has got it," Zimmer said. "It's a crazy time."

Seattle Seahawks coach Pete Carroll said they're trying to both win football games and avoid the coronavirus, which means winning the travel game. He thinks the NFL's reminders on following the protocol are good for everyone, but being this strict six months ago would've been better.

"Had we been this disciplined at the start, across the country, we would never see what we have seen," Carroll said. "But it's demanding. It's difficult. It's uncomfortable. Sometimes it's hard to make sense of it, but you got to do it anyway because it's the right way to handle it."

The New England Patriots are dealing with their own COVID-19 cases. Cornerback Stephon Gilmore, league's defensive player of the year last season, announced on social media he had tested positive and is asymptomatic. Quarterback Cam Newton was placed on the COVID-19 reserve list Saturday, with a defensive tackle from the practice squad added Tuesday.

New England, which is scheduled to host the Denver Broncos on Sunday, canceled practices for Wednesday and Thursday. The NFL already postponed the Patriots' most recent game a day before New England lost 26-10 to the host Kansas City Chiefs on Monday night. This Sunday, the Chiefs are set to host the Las Vegas Raiders, who placed defensive tackle Maurice Hurst on the COVID-19 reserve list Tuesday.

Newton and the Titans make up the 11 confirmed positive tests among players from testing last week. The NFL also said there were 15 new confirmed positives among personnel in results announced Wednesday out of 37,002 tests given to 7,981 players and team personnel last week.

Both Sills and Dr. Thom Mayer, the NFL Players Association's medical director, said the key is everyone following the protocol.

"The virus is still very much a threat not only to our season, but to the safety of everyone in our community," Mayer said in a release.

Bills coach Sean McDermott is busy preparing his team until told differently. He said no one's perfect and they're all fighting an uphill battle with how easily COVID-19 spreads. His players have had no positives after a 30-23 win Sunday at Las Vegas.

"We have a lot of trust and faith in the league," McDermott said of playing a game at Tennessee.

Pushing Bills-Titans to Monday night is challenging because Buffalo is scheduled to host Kansas City on Thursday, Oct. 15. That would force the NFL into further rearranging of the schedule.

The Bills aren't thinking of a forfeit right now.

"We'll handle that when the time comes," Bills safety Jordan Poyer said. "Right now, we're acting like we're playing. And when that moment comes, where they tell us this, that or the other, I think that's when we'll worry about it."

Bills quarterback Josh Allen said this virus can be as simple as one person going to a grocery store, and Baltimore Ravens wide receiver Marquise Brown said the test results show how cautious players must be away from the team facility.

"It's not just about you," Brown said. "It's about the whole NFL."

Asked about the chances of the NFL completing this season, Miami Dolphins quarterback Ryan Fitzpatrick said he thinks everyone is very interested in what happens the next few days.

"Everybody's confidence level is probably a little less than a few weeks ago," he said. "Two weeks ago everybody was riding high. It's amazing to see what happened in Tennessee so quickly."

Cleveland Browns quarterback Baker Mayfield had a simple suggestion to keep all of the NFL playing.

"Just wear your masks," Mayfield said. "We all want to play football. Everybody has to do it. Just do it."


AP Pro Football Writers Barry Wilner and Dave Campbell and Sports Writers Dave Ginsburg, Kyle Hightower, Will Graves, John Wawrow, Steve Wine, Tom Withers and Tim Booth contributed to this report.