ANN ARBOR, Mich. (AP) — Michigan State President Samuel Stanley publicly apologized Sunday for a “violent” skirmish in which Spartans football players appeared to attack Michigan players in a stadium tunnel after losing to the rival Wolverines.

“I’m extremely saddened by this incident and the unacceptable behavior depicted by members of our football program,” Stanley said in a statement. adding that those involved would be held responsible by coach Mel Tucker. “On behalf of Michigan State University, my heartfelt apology to the University of Michigan and the student athletes who were injured.

“There is no provocation that could justify the behavior we are seeing on the videos. Rivalries can be intense but should never be violent.”

The scuffle broke out in the Michigan Stadium tunnel after the fourth-ranked Wolverines beat the Spartans 29-7 Saturday night. Social media posts showed at least three Michigan State players pushing, punching, and kicking Michigan’s Ja’Den McBurrows in and near a hallway that doesn’t lead to either locker room.

McBurrows and defensive back Gemon Green went up the tunnel, walking alongside the Spartans, after the game while much of Michigan’s team was waving them off the field after beating their in-state rivals for the first time in three years.

Michigan coach Jim Harbaugh said Saturday night that one of the players, who he did not identify, might have a broken nose. A social media post on Sunday showed a Wolverine, who appears to be Green, getting roughed up by Spartans.

“Two of our players were assaulted,” Harbaugh said. “I saw on the one video. 10 on one. It was pretty bad. It needs to be investigated.”

Tucker said in a tweet Sunday that his program will cooperate with law enforcement and the Big Ten in any investigation.

“As Spartans, our program has a responsibility to uphold the highest level of sportsmanship. While emotions were very high at the conclusion of our rivalry game at Michigan Stadium, there is no excuse for behavior that puts our team or our opponents at risk,” Tucker said. “In complete cooperation with law enforcement, the Big Ten Conference and MSU and UM leadership, we will evaluate the events in Ann Arbor and take swift and appropriate action.”

University of Michigan Deputy Police Chief Melissa Overton said an investigation is underway in partnership with Michigan State police, and Michigan’s athletic department and football program.

“The investigation takes some time,” Overton said Sunday.

Stanley said the university will be cooperating with all related investigations by law enforcement and the Big Ten.

The Big Ten said in a statement: “The conference is currently gathering information, will thoroughly review the facts, and will take appropriate action.”

It was the second straight game at Michigan that included an altercation in the long, narrow tunnel that goes from the locker rooms to the field.

Earlier this month, Penn State coach James Franklin said a policy change was needed to provide a more orderly use of the tunnel.

Some heated words were exchanged, and Michigan players said Penn State players threw peanut butter and jelly sandwiches at them as the teams headed to the locker room at halftime of a close game the Wolverines ultimately won in a 41-17 rout on Oct. 15.

Harbaugh said Franklin acted as a “ringleader” and claimed the Nittany Lions stopped in the tunnel to prevent his team from accessing its locker room.