According to NBC, after the Thursday rally, some of Trump's supporters were surrounded and punched by his opponents.
The broadcaster added that Trump's opponents threw eggs, bottles and food at their rivals.
During all his campaign, the Republican frontrunner has been widely criticized for his controversial statements, which have at times targeted immigrants, Muslims, and women. Meanwhile, Hillary Clinton, who is expected to win the Democratic Party nomination, is being investigated by the FBI and may face an indictment.
The United States is expected to elect its new president on November 8, 2016.