INDIANAPOLIS — University of Notre Dame students are now subject to mandatory coronavirus testing with stricter penalties if they leave town before getting their test results after thousands of fans stormed the football field and threw parties to celebrate a double-overtime upset over Clemson.

The mass of students, players and coaches crammed close together on the field in the minutes following the Fighting Irish's 47-40 win Saturday night in South Bend, Indiana, over then-No. 1 Clemson. Many were not wearing masks or had them pulled down.

All Notre Dame students are required to undergo coronavirus testing before they leave South Bend for the extended winter break, Notre Dame President the Rev. John Jenkins told students in an email Sunday night. Jenkins didn't specifically reference the storming of the field, but rather "many gatherings" over the weekend.

If a student is exposed or tests positive, they will be required to quarantine on campus for two weeks. If students don't complete the mandatory coronavirus test — or if they leave before they receive their test results — they will be prevented from registering for classes, university officials said.

The campus has also introduced a zero-tolerance rule for gatherings that do not follow safety guidelines. Any student hosting a large gathering will face "severe sanctions."

"As exciting as last night's victory against Clemson was, it was very disappointing to see evidence of widespread disregard of our health protocols at many gatherings over the weekend," Jenkins said in his letter. In addition to the game, numerous parties were held across campus.

Following the win, Notre Dame moved up two spots to No. 2 in The Associated Press college football poll, while Clemson dropped to No. 4.

The celebration came just two days after Jenkins released a video warning students about spikes in COVID-19 cases on campus and imploring them to redouble their efforts to follow safety measures. Notre Dame reported 24 new COVID-19 cases on Friday, with 220 active cases overall. The university has reported 1,355 positive cases since the start of the fall semester.

Jenkins has come under criticism in recent weeks after he failed to wear a mask at a White House Rose Garden ceremony at which President Donald Trump introduced Amy Coney Barrett as his nominee to the U.S. Supreme Court. Jenkins, who tested positive for COVID-19 days later, shook hands and sat shoulder-to-shoulder with others at the event.

Jenkins later apologized, admitting he had "failed to lead by example." Notre Dame's Faculty Senate formally expressed disappointment in his actions in a resolution passed Thursday.