The raucous scuffle that forced Donald Trump to postpone his campaign event in Chicago on Friday is heightening concerns about the violence - inducing environment at the Republican presidential front - runner’s rallies.Clashes erupted when Trump’s campaign managers asked thousands of his supporters at the University of Illinois to leave the arena due to security concerns. The angry rally - goers gathered inside and outside the arena and then confronted several hundred anti - Trump protesters, blaming them for the cancellation. Five people were arrested and two police officers were injured in the scuffle. Earlier in the day, Trump was interrupted by protesters several times during a rally in St. Louis, Missouri. It led to at least one injury and 32 arrests. Trump defended his supporters, encouraging them to attack protesters if they provoke violence. Protesters have been beaten, shoved, kicked and verbally abused during many of Trump ' s events. “Part of the problem and part of the reason it takes so long[to kick them out] is nobody wants to hurt each other anymore, ” he charged on Friday. “There used to be consequences. There are none anymore, ” Trump said. “These people are so bad for our country. You have no idea folks, you have no idea. ”[caption id = " attachment _ 47404 " align = " aligncenter " width = " 650 "]Protesters gather outside of Trump’s St. Louis rally.(AFP photo)[/ caption][caption id = " attachment _ 47403 " align = " aligncenter " width = " 650 "]An anti - Trump protester is removed by security during the Trump rally in Chicago.[/ caption][caption id = " attachment _ 47402 " align = " aligncenter " width = " 650 "]Chicago police block streets outside the Trump rally on Friday.(AFP photo)[/ caption][caption id = " attachment _ 47401 " align = " aligncenter " width = " 650 "]Demonstrators taunt supporters of Trump as they leave the rally at the University of Illinois.(AFP photo)[/ caption][caption id = " attachment _ 47400 " align = " aligncenter " width = " 650 "]Police break up skirmishes between demonstrators and supporters of Donald Trump that broke out after his rally was canceled at the University of Illinois in Chicago.(AFP photo)[/ caption][caption id = " attachment _ 47399 " align = " aligncenter " width = " 650 "] Protesters gather outside Trump's rally at at the University of Illinois in Chicago on Friday.[/caption]