FULL TITLE: Far-left and far-right groups clash in Portland: Four injured and 13 arrested as tensions flare between protesters on streets lined with more than 1,000 cops just hours after President Trump threatened to declare Antifa a 'terror organization' Police arrested at least 13 people and seized metal poles, bear spray and other weapons Saturday as hundreds of far-right protesters and anti-fascist counter-demonstrators swarmed downtown Portland, Oregon. Authorities closed bridges and streets to try to keep the rival groups apart. The city's mayor said the situation was 'potentially dangerous and volatile,' and President Donald Trump tweeted 'Portland is being watched...