A free-speech rally in Berkeley, California, on Saturday turned violent when pro-Trump attendees clashed with counter-protesters.The chaos erupted during a scheduled “Patriot’s Day” event that was sponsored by a pro-Trump group, according to the Los Angeles Times. The hundreds of counter-demonstrators dressed in black described themselves as anti-fascist protesters, the Guardian reported.People from both groups used improvised weapons, including sticks and empty Pepsi cans filled with concrete, to harm opponents. Local police reported that more than 20 people were arrested and at least a dozen were injured.