ANN ARBOR, Mich. -- Jim Harbaugh expects the four suspended Michigan State football players involved in roughing up two members of Michigan's team to be punished further, saying he "can't imagine that this will not result in criminal charges."
Harbaugh said that defensive back Gemon Green was punched by a Spartan in the Michigan Stadium tunnel shortly after the fourth-ranked Wolverines beat their in-state rival Saturday night and that teammate Ja'Den McBurrows was attacked when he tried to help.
McBurrows is seen on a video shared on social media being pushed, punched and kicked by multiple Michigan State players, who pulled him out of the tunnel and into a hallway that doesn't lead to either locker room.
Harbaugh said both players have injuries, adding that he did not know whether Green, a starting cornerback for a third straight season, would be cleared to play Saturday night at Rutgers.
"Right now we have an ongoing police investigation," Harbaugh said Monday. "What happened in the tunnel was egregious. Sickening to watch the videos, the ones that are on social media right now."
Harbaugh added that an ABC camera placed in a "higher elevation" shows "much more of what took place" during the incident.
"There needs to be accountability," he said. "There needs to be a full, thorough, timely investigation. I can't imagine this will not result in criminal charges. The videos are bad. It's clear what transpired. This is very open and shut. As they say, watch the tape.
"I'm coming from this from a perspective of being a parent. These young men are entrusted to me by their families and to our program, and we have the responsibility to each player to treat them like our own, and I take that responsibility very seriously. An apology will not get the job done in this instance. There should be serious consequences for the many individuals that are culpable."
Michigan State coach Mel Tucker announced Sunday night that linebacker Tank Brown, safety Angelo Grose, defensive end Zion Young and cornerback Khary Crump were suspended immediately.
Brown, Grose and Young are seen on video getting physical with McBurrows.
Video showing another angle inside the tunnel shows Michigan State defensive end Jacoby Windmon put his helmet back on his head, turn toward Green and get involved in the altercation.
Windmon was not one of the four players suspended, and the extent of his involvement is not fully known.
"Michigan State University football core values include integrity, discipline, unselfishness, toughness and accountability," said Tucker, who made the decision after "reviewing the disturbing electronic evidence."
McBurrows and Green went up the tunnel alongside the Spartans after the game while many of Michigan's team members were waving their rivals off the field and other Wolverines were celebrating near the stadium's student section.
"They were walking up the tunnel," Harbaugh said when asked why Green and McBurrows were not with the rest of their teammates.
Green has hired attorney Tom Mars, who has handled several eligibility cases for college athletes, to represent him in the assault case.
"When college football players brutally attack a member of the opposing team with their helmets, resulting in the player suffering a concussion and other injuries, an apology won't suffice," Mars said in a statement provided to ESPN. "There has to be severe consequences for this kind of misconduct. Not only does Gemon Green deserve to be compensated for his injuries, severe consequences in this case will deter others who might think they can get away with brutally beating an opposing player and only get a slap on the wrist. I've got news for the MSU players who did this to Gemon. They are going to feel the full wrath of the law."
University of Michigan Deputy Police Chief Melissa Overton said Saturday night that an investigation has begun in partnership with Michigan State police, Michigan's athletic department and the Wolverines football program. "The investigation takes some time," Overton said Sunday.
Tucker said the school is working with law enforcement, Michigan State and Michigan campus leadership, and the Big Ten Conference to evaluate what happened, including identifying other players who were involved in the altercations and contributing factors.
"The initial student-athlete suspensions will remain in place until the investigations are completed," said Tucker, whose head was touched in the tunnel by a fan in the stands Saturday night. The coach responded by swiping the fan's hand away.
Michigan State president Samuel Stanley apologized for the "violent" skirmish.
"I'm extremely saddened by this incident and the unacceptable behavior depicted by members of our football program," Stanley said in a statement. "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."
Harbaugh said Monday that an apology is not enough.
The Big Ten said Sunday that it is gathering information and plans to 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. On Oct. 15 against Penn State, 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 41-17.
Penn State coach James Franklin said afterward that a policy change was needed to provide a more orderly use of the tunnel. 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.
ESPN's Blake Baumgartner, Tom VanHaaren and Adam Rittenberg and The Associated Press contributed to this report.