Violent clashes erupted Monday when Richard Spencer, a leading figure in the white nationalist movement, visited Michigan State University to spread his message decrying diversity and taking aim at a society where "everything that is good is anti-white."

Fights broke out as some protesters hurled bottles, rocks and horse manure to block Spencer's supporters from entering the Pavilion for Agriculture and Livestock Education, a venue at the southern tip of campus where Monday's event was held. Punches were thrown as members of the two groups hurled insults at one another.

Throughout the event, protesters chanted:"Nazis go home."

"I'm a Michigan State graduate, and I wanted to show that Michigan State is not a place for hate," said Jacob Osojnak, 48, who traveled from his home in Naperville, Illinois, to attend the protest.

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.

Spencer's speech was originally set to run from 4:30-6:30 p.m., but he delayed the start of the event until 5 p.m. due to what he described as "chaos" outside.

Law enforcement were out in full force. Helicopters buzzed overhead as more than 100 officers clad in riot gear guarded the entrance to the pavilion and escorted some of Spencer's supporters inside. Dozens of police vehicles lined the street near the venue, and protesters at one point lied down on the street to block an armored vehicle moving down the road.

"I think there's some people that made some choices, some of those choices were outside the law, and we had a zero tolerance and enforcement was taken," Monette said.

Monday's event was the culmination of months of legal wrangling to bring Spencer to campus. Cameron Padgett, who organizes speaking appearances for Spencer, sued MSU in September for denying his request to rent space on campus for the event.

In January, Padgett and MSU reached a settlement. In an attempt to "minimize the risk of violence or disruption to campus," the settlement stipulated that the event take place at the pavilion on Monday, the first day of MSU's spring break.

In response to Spencer's appearance, a counter rally, dubbed the Celebration of Diversity Festival, was hosted at All Saints Episcopal Church in East Lansing. The event, sponsored by interfaith leaders, drew more than a hundred residents and local elected officials who aimed to combat Spencer's divisive message by emphasizing love, peace and diversity, organizers said.

"This was really an opportunity for us to strengthen our community and for people to have real positive feelings about who we are in the East Lansing area," said Rabbi Amy Bigman, a leader in the Interfaith Clergy Association of Greater Lansing, which sponsored the event.

A graduate of the University of Virginia and the University of Chicago, Spencer has been credited with coining the term "alt-right" and, according to news reports, has advocated for an "ethno-state" that would expel minorities. He gained notoritey for leading a torchlight march at what became a violent rally in Charlottesville, Virginia, last August.

Protests targeting Spencer's visit started about noon Monday at a commuter parking lot down the road from the pavilion. Attendees began marching toward the venue about 2 p.m. Clashes between protesters and Spencer's supporters started about an hour-and-a-half later.

At one point, more than 20 of Spencer's supporters marched south on Farm Lane toward hundreds of protesters who were gathered in and around the pavilion's parking lot. Verbal clashes ensued, punches were thrown, and police began taking people into custody. Some people were hit by rocks, water bottles and other objects. Police confirmed there was a report of an unknown chemical substance thrown into the crowd.

Whether any significant injuries occurred Monday was unknown. Monette said he was not aware of anyone being transported to the hospital by ambulance.

Spencer denied MLive.com and several other media organizations press credentials. But during a livestream of his speech he criticized protesters for treating his supporters with "hostility."

"No other group is treated with this kind of hostility," he said. "We're treated with this kind of hostility precisely because we're white. Precisely because we're the only ones who are showing what the real crisis is in modern America today and across the word."

Protesters, including those who demonstrated peacefully, said it was their duty to stand up to Spencer and his beliefs.

"This is America, and Nazis aren't welcome here," said Ben Pearson, a 27-year-old Warren resident. "We fought a war. I think Nazis, we had a chance with them, and we figured out we weren't going to do that again."

Although Monday wasthe first day of the university's spring break, that didn't stop Olivia Franklin, a senior studying neuroscience and German, from attending the protest.

"Just because MSU had to basically let Richard Spencer come out today, we as a community are going to fight against his ideals, his misogynist and racist ideals," she said. "Just because the law can protect you a little bit, we as a society and a community are going to push against you and we are going to fight back."