(Reuters) - Demonstrators briefly shut down an Arizona highway leading to a campaign rally for Donald Trump on Saturday while protesters rallied outside of Trump Tower in Manhattan to voice their opposition to the front-runner for the Republican presidential nomination. Television news footage of the demonstration outside Phoenix showed dozens of protesters blocking traffic while holding signs that read “Dump Trump” and “Shut Down Trump.”  The demonstrators eventually started marching down the highway. Later, some were seen nearing the rally at Fountain Hills, Arizona, before Trump arrived. Three people were arrested, according to police in Maricopa County, where Joe Arpaio, a well-known critic of U.S. immigration policy and an ardent Trump supporter, serves as sheriff. Video posted on news website Arizona Central’s Facebook page showed a truck driving through a large group of protesters. Officers from the county police department worked to clear demonstrators from the motorist’s path. A woman is seen crying and shouting for officers to take responsibility to stop the vehicle, while a deputy sheriff shrugs at the suggestion.  Later at a rally in Tucson, Arizona, Trump said the protests were “disgraceful,” and thanked police. “They arrested three people and everybody else left... They left!” Trump said to roaring cheers from the audience. “I love our police, but we should do a little bit more of that, you’d have a lot less protesters, you’d have a lot less agitators,” said Trump, who is favored to win his party’s nomination for the Nov. 8 presidential election. Several demonstrations also broke out during the later rally, prompting police to escort out a number of people.  Footage of the Tucson rally shows an attendee punching and kicking one demonstrator who is being escorted out. The clip also shows police removing the attacker. Trump has come under fire from rivals for fueling unrest with his rhetoric. This week, he warned of riots if Republicans denied him the nomination at the party’s convention. In Trump’s home city of New York, about 1,000 demonstrators marched from Central Park to Trump Tower, the billionaire developer’s signature building on Fifth Avenue. The crowd of mostly young people chanted and carried placards denouncing Trump. Some said police used pepper spray on them as they marched from the park.  Police were seen taking at least one person into custody. A spokesman for the New York Police Department could not immediately confirm whether any arrests were made or whether pepper spray was used.  Arizona, where political parties will hold primary elections on Tuesday, shares a long stretch of border with Mexico, and is a flashpoint for the issue of illegal immigration into the United States. Trump has made illegal immigration the signature issue of his campaign, earning the endorsement of Arpaio, the outspoken sheriff.  “Donald Trump has the right to be heard by the thousands of people who love him, support him and want him to be president of the United States,” Arpaio told CNN. Later, the sheriff, wearing civilian clothes, introduced Trump at the rally.  Trump rallies have grown increasingly unruly as the months-long campaign has progressed. An event in Chicago a week ago was canceled after protesters swarmed the venue. Last weekend, a man was arrested when he attempted to rush the stage where Trump was addressing a rally in Ohio. In another incident, a man who was caught on video punching an anti-Trump protester in the face at a North Carolina rally was arrested and charged with assault. Trump leads in opinion polls ahead of Arizona’s March 22 primary, according to a Real Clear Politics polling average, leading Senator Ted Cruz of Texas by 13 percentage points. 