Interim Chicago Police Superintendent John Escalante said five arrests were made and two police officers were injured at the University of Illinois at Chicago Pavilion on Friday night where the Republican presidential frontrunner was scheduled to hold his rally. When an announcement was made saying the rally was postponed, pushing and shoving broke out as it took about 30 minutes for police to clear the building.
In separate interviews on CNN, MSNBC and Fox News, Trump said he feared for the safety of the thousands in attendance.
"I just felt for the benefit of safety, I don't want to see people hurt," he told MSNBC shortly after his rally was postponed.
Trump claimed no one had been hurt at any of his rallies, despite an incident caught on video in North Carolina earlier this week in which a supporter allegedly punched a protester in the face. The supporter has since been charged.
"I don’t take responsibility. Nobody has been hurt at our rallies," Trump said on CNN, saying later: "Overall, I think we've been very mild with protesters."
On Saturday morning, Trump took to Twitter, writing, "The organized group of people, many of them thugs, who shut down our First Amendment rights in Chicago, have totally energized America!"
The Chicago Police Department said it had sufficient officers to handle any issues at the rally. Escalante said the Trump campaign hadn't consulted with the department before calling off the event.
Trump's rivals chided him Friday after he postponed the rally.
"There is only one presidential candidate who has violence at their events and I do think Donald needs to realize and take responsibility for the fact that some of the rhetoric he has used could be contributing to this environment that is growing increasingly disturbing for a number of Americans," Rubio said Friday in Naples, Florida.
"The seeds of division that Donald Trump has been sowing this whole campaign finally bore fruit, and it was ugly," Ohio Gov. John Kasich said in a statement. "Some let their opposition to his views slip beyond protest into violence, but we can never let that happen. I urge people to resist that temptation and rise to a higher level."
Trump has courted criticism for remarks appearing to encourage violence against the protesters who have increasingly been disrupting his rallies. Earlier in the day in St. Louis, he mocked those who interrupted his speech and were removed by police, telling them to "go get a job" and one to "go back to mommy."
"These are people that are destroying our country," he said in St. Louis, adding, "You know part of the problem and part of the reason it takes so long is no one wants to hurt each other anymore and they’re being politically correct the way they take them out so it takes a little longer."
After his rally in Chicago was called off, Trump said the protesters there weren't directing their anger at him.
"This has a lot to do with jobs," Trump told Fox News. "It has a lot to do with incompetent running of a country."
Trump was scheduled to hold rallies in Dayton and Cleveland, Ohio, and Kansas City, Missouri, on Saturday.
Rob Hess contributed to this report.