A Donald Trump rally in Chicago has been postponed for safety reasons due to protest activity, a Trump campaign staffer told Reuters.

The announcement that Trump would postpone the rally for another day led the crowd inside the University of Illinois at Chicago Pavilion to break out into raucous cheers.

Protesters rushed the arena floor in jubilant celebration. Many jumped up and down, with arms up in the air, shouting "Bernie! Bernie!" and "We stopped Trump!"​

Meanwhile, supporters of the candidate broke out into chants of "We want Trump! We want Trump!"

There were isolated physical confrontations between some members of the crowd after the event was cancelled.

There was no sign of Trump inside the arena on the college campus, where dozens of UIC faculty and staff had petitioned university administrators to cancel the rally. They cited concerns it would create a "hostile and physically dangerous environment" for students.

Trump: 'I think we did the right thing'

Trump says he postponed the event because he didn't "want to see people hurt or worse."

Trump told MSNBC in a telephone interview: "I think we did the right thing."

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Supporters of Republican presidential candidate Donald Trump, left, face off with protesters after a rally on the campus of the University of Illinois-Chicago was cancelled due to security concerns Friday, March 11, 2016, in Chicago. (Charles Rex Arbogast/Associated Press)

Trump attributed the protests not to objections to his policies but to general malaise in the United States — particularly among people upset they haven't been able to find jobs.

"It's anger in the country," he said. "I don't think it's directed at me. Just what's been going on for years."

Trump also spoke with CNN, saying, "The protesters are really ... some of them are very violent and I'm not even sure they can control themselves."

Trump told CNN he does not incite or condone violence.

Trump supporters and protesters alike filled the arena earlier Friday night for the rally for the U.S. presidential contender, with a handful of intense verbal clashes taking place before the Republican front-runner took the stage.

For the first time during his White House bid, the crowd at a planned rally appeared to be an equal mix of those eager to cheer on the billionaire businessman and those overtly opposed to his candidacy.

'Let them stay'

When one African-American protester was escorted out before the event started, the crowd erupted into chants of "Let them stay!"

Veronica Kowalkowsky, an 18-year-old Trump supporter, said before the event started that she had no ill will toward the protesters — but didn't think they felt the same way.

"I feel a lot of hate," she said. "I haven't said anything bad to anyone."

Hours before the event was scheduled to start, hundreds of people lined up outside the arena at UIC — a civil and immigrant rights organizing hub with large minority student populations. Trump backers were separated from an equally large crowd of anti-Trump protesters by a heavy police presence and barricades.

Some Trump supporters walking into the area chanted, "USA! USA!" and "Illegal is illegal." One demonstrator shouted back, "Racist!"

'Build a wall around Trump'

One protester, 64-year-old Dede Rottman of Chicago, carried a placard that read: "Build a Wall Around Trump. I'll Pay for It."

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A demonstrator is removed by Chicago police. (Chris Sweda/Chicago Tribune via AP)

Trump's visit created waves on the campus from the time it was announced. Dozens of UIC faculty and staff petitioned university administrators to cancel the rally, citing concerns it would create a "hostile and physically dangerous environment" for students.

Trump is facing intensifying criticism for the violent clashes between supporters and protesters. His rally earlier Friday in St. Louis was interrupted repeatedly by protesters, and police there said 31 people were arrested and charged with general peace disturbance. One person arrested outside the St. Louis venue was charged with third-degree assault.

Trump taunted the protesters in St. Louis from the stage at the city's Peabody Opera House, even as he promised that police and security would be "gentle" as they removed them.

'Go home to mommy'

"They're allowed to get up and interrupt us horribly and we have to be very, very gentle," Trump said in response to one of the interruptions. "They can swing and hit people, but if we hit them back, it's a terrible, terrible thing, right?"

He panned the protesters as weak "troublemakers," ordered them to "go home to mommy" or "go home and get a job" because "they contribute nothing."

"These are not good people, just so you understand," Trump said. "These are not the people who made our country great. These are the people that are destroying our country."

As Trump attempts to unify a fractured Republican Party, racially charged images of his supporters attacking protesters and allegations that he's inciting violence have cast new attention on the divisive nature of his candidacy.

It intensified this week, when a North Carolina man was arrested after video footage showed him punching an African-American protester being led out of a rally in that state on Wednesday. At the event, the billionaire real estate mogul recalled a past protester as "a real bad dude."

"He was a rough guy, and he was punching. And we had some people — some rough guys like we have right in here — and they started punching back," Trump said. "It was a beautiful thing."

'I'd rather be too strong than too weak'

Friday's gathering in St. Louis was his first public campaign event since, and Trump defended his conduct and lashed out at the press for making too much of the clashes.

"You know, they talk about a protest or something. They don't talk about what's really happening in these forums and these rooms and these stadiums," Trump said. "They don't talk about the love."

He added that he and his supporters aren't angry people, but they "do get angry when we see the stupidity with which our country is run and how it's being destroyed."

"I'd rather be too strong than too weak, by a long shot," he said.

With files from Reuters