German security forces in riot gear clashed with thousands of anti-capitalist protesters Thursday, using water cannons and pepper spray to clear a march in which a militant group with anarchist sympathies had a prominent presence, The Post reported. Riots continued when the summit began Friday as protesters burned cars and blocked roads. First lady Melania Trump was forced to miss an event with the spouses of other world leaders because protesters blocked her from exiting the guesthouse where she and the president are staying.