Berkeley Mayor Jesse Arreguin has called for authorities to tackle left-wing violence by classifying members of antifa, the loosely organized group of “anti-fascists” who believe that violence is acceptable in countering right-wing extremism, as a gang. A largely peaceful demonstration in Berkeley’s Martin Luther King Civic Center Park was disrupted Sunday by black-clad antifa counterprotesters, who jumped over police barriers and chased Trump supporters, according to multiple news reports.