Demonstrations in Portland to commemorate May Day Saturday turned violent overnight, with officials declaring a riot and arresting six people, one with a knife. Three separate Starbucks stores and a Hilton hotel in the Oregon city were marred by graffiti, and one man was charged with menacing cops with a knife, Portland police said on Twitter. May 1, or May Day, is celebrated in many nations as International Workers Day or Labor Day. Portland’s demonstration on Saturday began peacefully, police said, with about 100 people gathering in the city, including near a federal Immigration and Customs Enforcement facility. But the gatherings — about 30 people near the ICE facility and nearly 100 at Shemanski Park — grew increasingly violent by 10 p.m., with the mob breaking windows and spraying graffiti as it moved toward City Hall, Fox News reported. Police ultimately declared a riot, with cops making the arrests after 11 p.m., Fox said. Among them was Jeremiah Day, 22, who ran from police but was found by bike cops – and allegedly pulled a butterfly knife on the officers before being busted.