A bloodied protester has been filmed being escorted from a Donald Trump rally in St Louis on Friday as demonstrators shut the event down for ten minutes.

The black activist, who gave his name as Anthony Cage, was filmed being escorted into a police van by two St Louis officers with blood across his face and down the front of his sweater.

There had been signs of trouble as early as 8am when people began queuing outside the Peabody Opera House to get tickets, with large groups of pro and anti-Trump fans shouting at one another.

Police detain a man after a fight between supporters and opponents of U.S. Republican presidential candidate Donald Trump, ahead of his speech outside the Peabody Opera House in St. Louis, Missouri

The black activist, who gave his name as Anthony Cage, was filmed being escorted into a police van by two St Louis officers with blood across his face and down the front of his sweater

A bloodied protester was pictured after being taken from a Donald Trump rally in Missouri today after anti-Trump activists clashed with demonstrators

The rally was interrupted for ten minutes after activists made it inside the Peabody Opera House in St Louis, with Trump complaining about the delay, saying: 'The problem is nobody wants to hurt each other anymore'

A demonstrator is removed from inside the Peabody Opera House during Trump's rally in St Louis

Police move in to arrest a group of demonstrators after they began chanting slogans and waving banners comparing Trump to the KK during his rally in St Louis today

After a large number of demonstrators sneaked into the event and began a coordinated protest inside, Trump told the crowd: 'Part of the problem and part of the reason it takes so long is nobody wants to hurt each other anymore, right?

'And they're being politically correct the way they take them out. So it takes a little bit longer,' the River Front Times reported.

Demonstrators pulled off their jackets to reveal anti-Trump slogans, or produced banners, at least one of which compared Trump to the KKK.

Trump repeatedly summoned police to remove the demonstrators, and seemed to become irritated after it took ten minutes to escort them out.

It is not clear how the activist was injured, but there were multiple scuffles between Trump supporters and demonstrators.

Other reports indicated that the man was not arrested, but instead had his wounds treated and was allowed to walk free.

The fresh scenes of violence come after Trump supporter John McGraw, 78, was caught on camera hitting Rakeem Jones, 26, at another event in Fayetteville, North Carolina, on Wednesday.

Thousands of anti-Trump protesters, some Black Lives Matter activists and veterans of the Ferguson demonstrations, wave banners and chanted slogans outside the venue

Trump supporters were also out in force, with lines for the rally stretching around the block and thousands of people left to listen on loudspeakers outside

Police were forced to erect metal barriers between the two factions as tempers repeatedly threatened to boil over, with Trump supporters chanting 'build the wall'

Quizzed by Inside Edition on why he hit the black demonstrator, McGraw responded 'we don't know if he's ISIS', before adding: 'Next time we see him, we might have to kill him.'

In response to the alleged attack, R&B singer Chris Brown urged black protesters to travel in groups to avoid being attacked.

According to the New York Daily News, the singer said: 'Man, this s*** is getting crazy. Black people getting assaulted at f****ing rallies where you’re supposed to talk at.

'What you need to start doing - all these black people, go together 40, 50 deep. See what they do then. Keep touching us, motherf*****.'

Trump has repeatedly refuted allegations that his often incendiary rhetoric, particularly against Muslims and Mexicans, has incited violence.

Organizers at Trump rallies have also been advising attendees on how to deal with demonstrators, saying they should chant and wave banners while waiting for the authorities, and have warned against getting physically involved themselves.

Thousands of people turned out to hear Trump speak in Missouri on Friday with a line hours long stretching around the block for tickets to be allowed inside the 3,000 seat theater.

Thousands more were left standing outside where they listened to the speech on loudspeakers, with anti-Trump protesters chanting slogans nearby.

The fresh violence comes two days after John McGraw, 78 (left), was arrested after allegedly punching a black activist at a Trump rally (right) claiming 'we don't know if he's ISIS'

Security were forced to erect steel barriers to keep the two parties apart as tensions threatened to boil over, video from the event shows.

According to local reports, many of the anti-Trump protesters were from Black Lives Matter, and had previously been involved in rallies in Ferguson following the shooting of Michael Brown.

Trump had to answer questions at Thursday night's GOP debate about violence involving his supporters clashing with opponents at rallies.

Friday's gathering in St. Louis was his first public campaign event since Wednesday's rally, and Trump lashed out at the criticism.

'You know, they talk about a protest or something. They don't talk about what's really happing in these forums and these rooms and these stadiums,' Trump said. 'They don't talk about the love.'

He added that he and his supporters aren't angry people, but they 'do get angry when we see the stupidity with which our country is run and how it's being destroyed.'

Trump was quizzed over whether his rallies incite violence at the GOP debate on Thursday night, a claim he denied, saying people don't report on the 'love' shown by supporters

Local news stations reported queues of several hours long stretching around the block in order to hear Trump speak before he attends another event this evening in Chicago (pictured)

Trump supporters wait in line outside the UIC Pavilion in Chicago where Trump is expected to hold another rally tonight with more heavy security planned

Earlier Friday at a news conference in Palm Beach, Florida, Trump applauded his supporters who have taken on protesters who he says have gotten physical at his rallies.

'The audience hit back,' he said. 'And that's what we need a little bit more of.'

Later Friday, Trump will hold an evening rally at the University of Illinois at Chicago — a civil and immigrant rights organizing hub with large minority student populations.

Trump's visit has already created waves on the campus. Dozens of UIC faculty and staff petitioned university administrators to cancel the rally, citing concerns it would create a 'hostile and physically dangerous environment' for students. Chicago police plan a heavy presence.

Rep. Luis Gutierrez, student activists and longtime Chicago organizers are all planning to protest outside the university venue over issues that include what they called Trump's disparaging comments, particularly about Muslims and Mexicans.

'Donald Trump's campaign, it incites hatred and violence with the things he says with marginalized groups that are very prevalent UIC,' said Casandra Rebledo, a 19-year-old nursing student. 'This is something we feel is a form of empowerment.'

Trump speaks to supporters at his rally in St Louis today which had to be paused for ten minutes after a large group of protesters got inside and started shouting slogans

Republican candidate Donald Trump greets supporters at the end of a rally at the Peabody Opera House

Trump signs merchandise including books and hats at the end of his rally in St Louis today

Gutierrez said he had no plans to enter the event. Instead, he would rally in a parking lot outside with a message focused on welcoming all.

'We're not going to let Donald Trump take us back to the 1950s,' said Gutierrez, a Chicago Democrat, who has long rallied for immigrant rights. 'We've worked too hard.'

Organizers of a student-led group, who expected hundreds of participants, planned to meet on campus and march to the arena where Trump will speak and set up shop in a nearby parking lot.

Members of Black Lives Matter Chicago, which has held largely peaceful smaller protests following a police-involved shooting in Chicago, also planned to participate.

Chicago police said they were coordinating with the Secret Service, university police and fire department officials on logistics.