Police arrested dozens at a massive Los Angeles demonstration protesting President Donald Trump over the weekend.

The No Kings demonstration was part of a nationwide protest against the Trump administration, including Immigration and Customs Enforcement, which event organizers described as “masked secret police terrorizing our communities.” Throughout the day, thousands participated in the event in California’s largest city before the demonstration grew tense. In the late afternoon, a small group of protesters began clashing with authorities outside the Metropolitan Detention Center, the site of other protests in recent months and where ICE holds detainees.