Last night, the protests around Donald Trump’s rally in San Jose, California, became violent. Protesters carrying Mexican flags chased Trump supporters while police, who were seemingly there to protect from property damage, watched. At least one American flag was burned. A woman wearing a Trump jersey was surrounded and egged. When a freelance photographer following the Trump campaign called 911 to report a Trump supporter getting sucker punched, he was placed on hold.

In recent campaign stops in New Mexico and California, the protests outside Trump rallies also became violent. When police moved to disperse the protesters after the San Jose rally ended, one protester shouted back, “We don’t follow the law!” Afterwards, San Jose police said in a statement they “made a few arrests tonight,” but there was no reported property damage and only one officer was assaulted.

Lost amidst the horse-race coverage of the political campaign last week, Trump announced that he was going to focus on 15 states in the general election. Trump said that he’d fight for New York and California — a head scratching statement, as they are Democrat strongholds. “I think now we know why Trump has decided to campaign a lot in California, even though he stands no chance of winning it,” wrote Josh Barro, senior editor of Business Insider. Trump is a master media manipulator. You saw his skill this week when he shifted focus from his donations to veterans to how the media was doing their job. Campaigning in California brings his supporters in close proximity to those who loathe his campaign and are ready to throw punches. That sparks violence. Violence breeds fear as pictures of bloodied Trump supporters circulate around the nation. In turn, that helps crystalize Trump’s message, and can help him win support.