Clashes erupted Saturday between supporters and opponents of President Trump at a park in Berkeley, Calif., where police made a number of arrests.

A group called Liberty Revival Alliance planned a pro-Trump rally at Martin Luther King Jr. Civic Center Park, the Los Angeles Times reported. Anti-Trump protesters also gathered at the site.

The Berkeley Police Department said that it had made more than a dozen arrests as of early Saturday afternoon, and expected to make more. Police also have seized many items that were prohibited from the area.

Here are some of the prohibited items that have already removed from the park today. https://t.co/3qx3smYwgk pic.twitter.com/A70VCxFYEu — Berkeley Police (@berkeleypolice) April 15, 2017

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“A large number of fights have occurred and numerous fireworks have been thrown in the crowds,” Berkeley police said in a news release. “There have also been numerous reports of pepper spray being used in the crowd.”

The police department later said that the protesters were expanding the area of their demonstrations.

Violent fights break out during #PatriotsDay event in Berkeley, CA. pic.twitter.com/hnzs8QzhWJ — Golden Gate Xpress (@XpressNews) April 15, 2017

Absolutely chaotic scenes in Berkeley where pro- & anti-Trump protesters are clashing. @BuzzFeedNews also on scene: https://t.co/GHfElQPq6U pic.twitter.com/XX5mR0s7LC — David Mack (@davidmackau) April 15, 2017

Berkeley has been the site of a number of protests in recent months. A pro-Trump event at the Civic Center Park in March also got heated.

The University of California-Berkeley was the site of protests in February as well due to then-Breitbart editor and outspoken Trump supporter Milo Yiannopoulos, who was scheduled to speak at the school.

Updated: 5:40 p.m.