The Donald Trump rally at UIC Chicago Pavilion in Chicago was postponed on Friday evening after thousands of his supporters had already began to fill the venue, due to a massive protest surrounding the building.

Many different activist groups converged for a march to the venue where they began to link hands to block the roadway. Protesters were both inside and outside the building, and many of them appeared to be UIC students.

Anyone who was wearing anti-Trump clothing or carrying protest signs were not allowed into the event, however, many demonstrators made their way inside and were met with a hostile crowd.

— pat muldowney (@patmuldowney) March 12, 2016

After the announcement that the event was cancelled, fights broke out both inside and outside the venue. A demonstrator also made his way to Trump's podium.

— Kevin Pang (@pang) March 12, 2016

— agitator in chief (@soit_goes) March 12, 2016

— WGN TV News (@WGNNews) March 12, 2016

​Approximately 180 members of the university's faculty had signed a letter to the chancellor expressing concern about the candidate speaking at the campus. UIC is said to be one of the most diverse universities in the nation.

CBS Chicago station WBBM reported that a Chicago police officer was injured during the clashes. CBS said its news reporter Sopan Deb was detained by law enforcement while covering the protest.

Earlier in the day, as Trump spoke in St. Louis, a black Ferguson activist was beaten and bloodied by one of the candidate's supporters as he used a bullhorn to denounce racism. Videos uploaded to social media also showed Trump's followers shouting hate speech at the protesters, unsurprisingly, as Trump himself seemed to encourage violence from the podium. After being interrupted, the presidential hopeful lamented that it was a “shame” that protesters had to be treated “gently” by police.