Chicago - (AP)  - Republican presidential candidate Donald Trump canceled one of his signature rallies on Friday, calling off the event due to safety concerns after protesters packed the arena where he was scheduled to speak.

The announcement the billionaire businessman would postpone the rally led a large portion of the crowd inside the University of Illinois at Chicago Pavilion to break out into raucous cheers. Many rushed onto the floor, jumping up and down with their arms up in the air.

"Trump represents everything America is not and everything Chicago is not," said Kamran Siddiqui, 20, a student at the school who was among those celebrating. "We came in here and we wanted to shut this down. Because this is a great city and we don't want to let that person in here."

Some supporters of the Republican front-runner started chanting "We want Trump! We want Trump!" in response to the celebrations, and there were some isolated physical confrontations between members of the crowd. Chicago police said they made some arrests.

"It's a shame," said Trump supporter Bill Tail, 43, of the Chicago suburb of Oaklawn. "They scream about tolerance, but are being intolerant themselves. That doesn't make sense."

As Trump attempts to unify a fractured Republican Party ahead of next week's slate of winner-take-all primary elections, the confrontations between his legion of loyal supporters and protesters who accuse him of stoking racial hatred have become increasingly contentious, underscoring concerns about the divisive nature of his candidacy.

A North Carolina man was arrested after video footage showed him punching an African-American protester being led out of a Trump rally in that state on Wednesday. At that event, Trump 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."

At Trump's rally earlier Friday in St. Louis, he was repeatedly interrupted by protesters. Police there charged nearly three dozen people with general peace disturbance and one person with assault.

Texas Sen. Ted Cruz, second in delegates to Trump in the GOP race, said late Friday that the billionaire has created "an environment that encourages this sort of nasty discourse."

"When the candidate urges supporters to engage in physical violence, to punch people in the face, the predictable consequence of that is that is escalates," Cruz said. "Today is unlikely to be the last such incidence."

In a telephone interview after postponing his event in Chicago, Trump said he didn't "want to see people hurt or worse" at the rally, telling MSNBC, "I think we did the right thing."

But Chicago police said they had sufficient manpower on scene to handle the situation and did not recommended Trump cancel the rally. That decision was made "independently" by the campaign, said police spokesman Anthony Guglielmi.

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