Protests against the shootings of two black men by police officers shut down main arteries in a number of US cities on Saturday, leading to numerous arrests, scuffles and injuries in confrontations between police and demonstrators. Undeterred by heightened concerns about safety at protests after a lone gunman killed five police officers in Dallas Thursday night, organizers went ahead with marches in the biggest metropolis, New York City, and Washington D.C., the nation's capital, among other cities. It was the third straight day of widespread protests after the fatal shooting of Alton Sterling, 37, by police in Baton Rouge on Tuesday and the death of Philando Castile, 32, on Wednesday night in a St. Paul, Minnesota suburb, cities which both saw heated protests on Saturday. The most recent shooting deaths by police come after several years of contentious killings by law enforcement officers, including that of Michael Brown, a teenager whose death in the summer of 2014 caused riots and weeks of protests in the St. Louis suburb of Ferguson. On Saturday evening, hundreds of protesters shut down I-94, a major thoroughfare linking the Twin Cities, snarling traffic. Protesters, told to disperse, threw rocks, bottles and construction rebar at officers, injuring at least three, St. Paul police said. Police made arrests and used smoke bombs and marking rounds to disperse the crowd. — Reuters