Dozens of protesters were mostly peaceful as Trump gave his speech inside the Pacific Amphitheater. After the event, however, the demonstration grew rowdy and spilled into the streets.

At least four people were arrested and one Trump supporter had his face bloodied in a scuffle as he tried to drive out of the arena. One man jumped on a police car, leaving its front and rear windows smashed and the top dented in and other protests sprayed graffiti on a police car and the venue’s marquee.

Dozens of cars—including those of Trump supporters trying to leave— were stuck in the street as several hundred demonstrators blocked the road, waved Mexican flags and posed for selfies. Police in riot gear and on horseback pushed the crowd back and away from the venue. There were no major injuries and police did not use any force. The crowd began dispersing about three hours after the speech ended.

Earlier in the evening, a half-dozen anti-Trump protesters taunted those waiting to get into the venue. Trump supporters surrounded one man who waved a Mexican flag and shouted “Build that wall! Build that wall!”—a reference to Trump’s call to create a barrier between the United States and Mexico to stop illegal border crossings.

At one point, seven women wearing no shirts and Bernie Sanders stickers over their breasts entered the square outside the amphitheater. They said they were protesting Trump’s lack of engagement on issues of gender equality and women’s rights.

“I feel like he wants to make America great again, but certainly not for women, for the LBGTQ community or for the lower class,” said one of the women, Tiernan Hebron. “He has, like, done nothing to help with gender equality or women’s rights or reproductive rights or anything.”

Trump has drawn large crowds across the country as he has campaigned for the White House and some of his events have been marred by incidents both inside and outside these venues.

Earlier this week, a Trump rally in nearby Anaheim, California turned contentious when his supporters and counter protestors clashed, leaving several people struck by pepper spray. Trump was not present.

Trump has drawn large crowds to most of his campaign events, and Thursday was no exception. The Pacific Amphitheatre was filled to its capacity of about 18,000 and many hundreds more were turned away.

Ly Kou, 47, of Ontario, said she likes Trump because he has vowed to put the country first.

“It’s obvious that America loves Trump,” said Kou, who is from Laos, as she pointed at the waiting throng. “This thing about him being racist? Look around the crowd.”

Trump was traveling from the rally site to the state’s Republican convention in Burlington in the San Francisco Bay area.