Their faces hidden behind black bandannas and hoodies, about 100 anarchists and antifa- "anti-fascist" - members barreled into a protest Sunday afternoon in Berkeley's Martin Luther King Jr. Civic Center Park. Jumping over plastic and concrete barriers, the group melted into a larger crowd of around 2,000 that had marched peacefully throughout the sunny afternoon for a "Rally Against Hate" gathering. Shortly after, violence began to flare. A pepper-spray-wielding Trump supporter was smacked to the ground with homemade shields. Another was attacked by five black-clad antifa members, each windmilling kicks and punches into a man desperately trying to protect himself. A conservative group leader retreated for safety behind a line of riot police as marchers chucked water bottles, shot off pepper spray and screamed, "Fascist go home!" All told, the Associated Press reported at least five individuals were attacked. An AP reporter witnessed the assaults. Berkeley Police's Lt. Joe Okies told The Washington Post the rally resulted in "13 arrests on a range of charges including assault with a deadly weapon, obstructing a police officer, and various Berkeley municipal code violations." And although the anti-hate and left-wing protesters largely drowned out the smaller clutch of far-right marchers attending a planned "No to Marxism in America" rally, Sunday's confrontation marked another street brawl between opposing ends of the political spectrum - violence that has become a regular feature of the Trump years and gives signs of spiraling upward, particularly in the wake of the violence in Charlottesville. "I applaud the more than 7,000 people who came out today to peacefully oppose bigotry, hatred and racism that we saw on display in Charlottesville," Berkeley Mayor Jesse Arregun said in a statement. "... However, the violence that small group of protesters engaged in against residents and the police, including throwing smoke bombs, is unacceptable.