Trump Protesters Clash With Police Outside Trump Rally

Police on horseback and in riot gear pass a damaged police car as they break up a demonstration outside Republican presidential candidate Donald Trump's campaign rally in Costa Mesa, California, on April 28, 2016.

Police arrested 20 people outside a Donald Trump rally in California Thursday night amid the worst violence since last month's cancelation of a campaign event in Chicago.

Some anti-Trump demonstrators are arrested after the rally at the Pacific Amphitheatre. Hundreds of people, most of them apparently anti-Trump protesters, blocked an intersection and some jumped on cars outside the Orange County Fairgrounds, where Trump gave a speech to thousands Thursday night.

A demonstrator climbs a traffic light outside the rally.

There were no major injuries, the Orange County Sheriff's Department said, adding that the crowd had dispersed by 11 p.m. local time (2 a.m. ET).

A Trump supporter clashes with protesters outside the rally.

Demonstrators sit in front of a line of police in riot gear outside the rally.

Protests at Trump rallies have occasionally ended in clashes. In March, a planned Trump rally in Chicago descended into chaos, with fistfights breaking out between supporters and opponents of the controversial candidate.

Police in riot gear arrive to break-up a demonstration outside the rally.

A protester waves a Mexican flag in front of police in riot gear.

Police in riot gear arrive to break up the demonstration.

Protestors are pushed off the street by law enforcement after the rally.

Donald Trump greets supporters after the rally.

Donald Trump arrives to speak at the rally.

Protesters are separated from Trump supporters by a line of riot police officers outside the rally. Trump has begun campaigning in California ahead of the June 7 primary.

Trump supporters cheer at the rally.

Elaine Theiss waits to hear Donald Trump speak at a campaign rally in Costa Mesa, California, on April 28.