Armored police vehicles and officers wearing riot gear were present and promptly broke up the brawls before handcuffing half a dozen of the participants, the outlet reported.
Between 12 and 24 people were arrested for a range of felony and misdemeanor offenses, including weapons violations and hindering and obstructing police, said MSU Police Capt. Doug Monette.
One of those arrested was Jonathan Kolanowski, a supporter of Spencer who allegedly pointed a gun at protesters. Bottles and rocks were also thrown during the skirmishes.
Students are on spring break.
Spencer is a highly controversial figure and often draws massive crowds of both protesters and supporters.
The protests delayed Spencer's speech by 30 minutes.
Spencer is the leader of the National Policy Institute, or NPI. One man said he was on the fence about Spencer as a person but came out of the speech with a better understanding.
"He is full of hate - that's all", she said. Officials at Michigan State did not immediately respond to a request for comment.
"The ideas that they espouse: genocide, white supremacy, fascism, are anti-American and unsafe to our people, to our nation, to Americans", he said.
Spencer popularized the term "alt-right" to refer to a fringe movement that's a mix of white nationalist and anti-Semitic beliefs.
The event was ticketed and Spencer was given control over who is allowed in, denying several local media organizations from purchasing tickets. "I'm still here, we're always going to be here".
"The safety and security of our campus community remains our top priority", Monette said.