Violence erupted Thursday night outside a campaign rally for Donald Trump in Costa Mesa, California.

Trump  was addressing thousands of supporters outside the Orange County amphitheater when hundreds of protesters lined the street, blocked traffic, and waved American and Mexican flags. 

The situation became violent when demonstrators began stomping on police cars and smashing car windows.

One confrontation even turned bloody when protesters threw rocks and beer bottles and attacked a Trump supporter. The video above shows a bloody Trump supporter walking out of a skirmish, claiming that the protesters stole his hat. "She stole my s**t," the protester said. The protesters claimed the man had assaulted a girl, which led to the attack that left him bloody.

Another incident involved a young woman's car being ransacked as she tried to exit the rally. As the anti-Trump crowd surrounded her, the video shows that they subsequently spit on the car, yelled obscenities, and threatened to set the car on fire.

The protesters claimed they came to the rally to show opposition to Trump's proposal to build a wall along the United States-Mexico border. The Los Angeles Times reported that the crowd appeared to be "mostly Latinos in their late teens and 20s." One protester named Daniel Lujan said he knew violence would erupt and that Trump "deserves what he gets."

How did Trump respond? The GOP front-runner tweeted his appreciation to the city of Costa Mesa. "Thank you Costa Mesa, California!" Trump wrote. "31,000 people tonight with thousands turned away. I will be back! #Trump2016."