Twenty people were arrested outside Donald Trump's rally at the OC Fair and Event Center in Costa Mesa, California, on April 28 (video below).
Hundreds of protesters stood on nearby streets and blocked traffic outside the rally, notes NBC News.
One police car had its windows smashed, a man was seen jumping on top of it, while another person wrote on the vehicle and several others attempted to flip the cruiser over.
Protesters shouted, "Racists go home!," and chanted, "Whose streets? Our streets!," when police on horses in riot gear attempted to control the crowd.
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In one bizarre and dangerous moment, a car started doing donuts near the crowd; there were also rocks thrown at motorists.
Inside the OC Fair and Event Center, Trump brought people carrying photographs of their family members who were killed by undocumented immigrants on stage, notes the Los Angeles Times.
Trump also promised to build his border wall, which brought cheers from the crowd.
American and Mexican flags were carried by protesters outside Trump's event.
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David B. Villanueva, one of the anti-Trump demonstrators, told the newspaper: "Protesters chose to bring out the Mexican flag to demonstrate their culture and not their nationality. In this election year, I find the fact that people are waving Mexican flags more important than people waving American flags because of the diversity within our own American culture."
According to Villanueva, the chaos among the protesters was caused by the last-minute news about Trump's rally, which didn't give civil rights leaders enough time to mount an organized protest.
Hundreds of Trump supporters were turned away from the event because of the lack of seating at the full-capacity rally, which might explain some of the conflict outside the event, KNBC notes.
Seventy-seven percent of Latinos in California do not like Trump, but the GOP front-runner leads among Republicans, according to a University of Southern California, Los Angeles poll.