FOUNTAIN HILLS, Ariz. — Protesters on Saturday blocked an Arizona highway that served as a route into this Phoenix suburb where Republican presidential front-runner Donald Trump had a campaign rally scheduled for 2 p.m. Eastern time.

The protesters first blocked traffic with a pair of pickup trucks, with banners reading "Comb Over Racism: Dump Trump" and "Shut down Trump," as seen from aerial footage aired by Fox 10 Phoenix, a local TV affiliate. As the trucks were later towed away to clear a path for traffic, protesters formed a human wall. Traffic finally resumed along the highway, a main route into the suburb hosting the rally, after officers began arresting protesters. Three were arrested, Maricopa County Sheriff Joe Arpaio said in his remarks introducing Trump. Protesters also gathered Saturday in New York City.

Meanwhile, several thousand people were at Fountain Park in Fountain Hills for Trump's rally. About 1,500 people waited inside the secure rally area with several thousand watching from nearby. Unlike most of Trump's rallies, reporters were forbidden from mingling with the crowd, even hours before the rally started.

About three miles away from the park, a few dozen protesters gathered near the town's welcome sign with anti-Trump signs reading "Stop racism" and "Deport racism."

Only a dozen or so protesters stood at the entrance to Trump's rally. One young woman held a sign reading "Love Trumps hate." A 47-year-old father of five had a sign of an orange pig and Trump that said:  "Cute orange pig, Pompous orange pig." A small group of high school students also stood watch with signs, although they said most of their friends had instead infiltrated the rally.

By the time the road had been blocked, Trump's rally was already packed and a long line of people waited to get in -- so while the protesters made a point by fouling up traffic, they did little to prevent Trump from getting a full audience.

For months, Trump's rallies have attracted protesters, but the number and intensity of protests has dramatically increased. Earlier this month, Trump canceled a rally at the University of Illinois at Chicago for security reasons because thousands of protesters had gathered inside and outside the rally, often violently clashing with Trump supporters.

Arizona's Republican and Democratic primaries are on Tuesday, and immigration is a dominate topic of the 2016 presidential race. Last summer Trump laid out a series of controversial immigration reforms, including building a massive wall along the border with Mexico, deporting the millions of immigrants illegally in the country and ending birthright citizenship.

Trump is expected to be joined onstage by Maricopa County Sheriff Joe Arpaio, whose long tenure has been marked with one controversy after another, including his treatment of prisoners and using his authority to target illegal immigrants.