Trump rally protesters
Protesters against Donald Trump gather outside the UIC Pavilion in Chicago before trouble flared Reuters

A police officer has been wounded during protests at a Chicago rally for Republican US presidential candidate Donald Trump which was cancelled because violence. The unnamed law enforcement official was filmed with blood streaming down his face.

The video of the officer was taken by local resident Jeff Orr, who said that the footage had been shot at the junction of Van Buren Street and Racine Avenue in Chicago, just two blocks away from the event venue's at the UIC Pavilion in Chicago.

Talking to local broadcaster NBC Chicago, Orr said that there had been a mix of protesters and Trump supporters, but that the scene had been so confusing that he had not known what had happened. "It was a very tense situation that indicative of the tension in America right now," he told the TV channel.

According to the Chicago Fire Department two police officers were wounded attending the scene of the protests. One of the officers needed stitches after being hit on the head with a bottle, but the department could not confirm whether this was the officer in Orr's video. Neither officer sustained life-threatening injuries.

During a hastily arranged press conference John Escalante, interim superintendent of Chicago's police force, said: "It is unfortunate that parties on both sides allowed their political views to become confrontational, and that's unfortunately resulted in that scuffling and the arrests that were made. We were confident that we had the right security for the event."

On Friday, 11 March, it was reported that up to five arrests had been made during the trouble. Several hundred demonstrators packed the arena hours prior to Trump's appearance. Some of them were involved in altercations with backers of the Republican front-runner.

Trump's campaign said in a statement that it had decided to postpone the event after holding discussions with Chicago police and that it would be held on "another date" that is yet to be confirmed.

Trump's rival for the presidential nomination Ben Carson has backed the billionaire after dropping out of the race for the White House. He tweeted: "I endorse @realDonaldTrump. It's time to unite behind the candidate who will beat Hillary Clinton and return government to, "We the People"