Donald Trump has called off a rally in Chicago after protests against the Republican presidential front-runner led to violent clashes.
Hundreds of protesters gathered outside the venue at the University of Illinois hours before Mr Trump was due.
Inside the auditorium, fighting broke out between supporters and protesters, who waved flags and chanted.
A statement from Mr Trump's campaign said the candidate decided to postpone the event after meeting with police.
But a Chicago Police Department spokesman said the force was not consulted in the decision to postpone the rally.
At the rally there were chants for Mr Trump from his supporters and for Democratic candidate Bernie Sanders from some of the protesters.
There were several violent clashes, some sparked by Trump supporters attempting to wrestle flags from protesters.
One protester had to be physically removed from the stage by what appeared to be a Secret Service agent.
Violent clashes continued outside the venue, with helicopter footage showing chaotic scenes as police attempted to control the large crowds.
The full statement from Mr Trump's campaign read: "Mr. Trump just arrived in Chicago and after meeting with law enforcement has determined that for the safety of all of the tens of thousands of people that have gathered in and around the arena, tonight's rally will be postponed to another date.
"Thank you very much for your attendance and please go in peace."
Speaking to Fox News after the events, Mr Trump denied using hate speech or playing any part in fostering division.
"I represent a large group of people that have a lot of anger," he said. "There is tremendous anger out there on both sides."
Discussing the decision to cancel the rally, he said: "I think it was a very good thing we did, I think it was an intelligent decision."
Staff at the university had earlier petitioned administrators to cancel the rally, citing concerns it would create a "hostile and physically dangerous environment" for students.
Earlier on Friday, 32 people were arrested after protests at a rally held by Mr Trump rally in St Louis, Missouri.
Mr Trump was repeatedly interrupted by the protesters, who he called a "disgrace".
These latest clashes come just a day after a Trump supporter was charged with assault after multiple videos showed him punching a protester at a campaign rally in North Carolina.
The billionaire later said that the supporter's actions were "appropriate".