Punches, and at least one egg, were thrown outside the venue where Donald Trump, the presumptive Republican U.S. presidential candidate, was holding a campaign rally Thursday night in San Jose, California.
Several hundred demonstrators and Trump supporters clashed before and after the rally. Police dressed in riot gear formed lines to try to keep the two sides apart.
Protesters jumped on cars and threw traffic cones and water bottles at police. Others snatched hats -- with Trump's campaign slogan "Make America Great Again" -- from his supporters and set the items on fire. And one female Trump supporter, who was videotaped taunting protesters, was cornered and pelted with an egg.
Police said there were no immediate reports of injuries and no major property damage, The Associated Press reported. Local media, however, reported several dozen fistfights had broken out and noted several people were seen with bloody wounds.
Four people were taken into custody, according to the AP, but police had not released final numbers late Thursday.
San Jose Mayor Sam Liccardo, a supporter of Democratic presidential front-runner Hillary Clinton, criticized the Republican candidate for igniting problems in cities that local police departments have to deal with.
"At some point Donald Trump needs to take responsibility for the irresponsible behavior of his campaign," Liccardo said.
Inside the rally, Trump revved the crowd up by saying to stop illegal drugs from coming into the United States from the south, he would build a wall on the U.S. border and have Mexico pay the bill.
"We are going to build that wall, don't even think about it," he said as his supporters chanted "build that wall."
Debbie Tracey, a U.S. Navy veteran from San Jose, told the AP she is a Trump supporter and supported his calls for a wall on the border.
"I'll go help build the wall because if you are going to come to this country, land of opportunity, you should be here legally," she said.
The rally took place hours after Clinton gave a scathing speech in San Diego where she said Trump was "unfit" to serve as president.
Protests have become more common at Trump events. Last month in New Mexico, protesters clashed with police, dozens were arrested last week in San Diego after Trump held a rally, and the candidate canceled a rally in Chicago in March after clashes between his supporters and protesters.