PITTSBURGH (AP) — Pittsburgh’s mayor says he has “serious concerns” about the tactics used in the arrest of a protester during a march Saturday that drew condemnation from the American Civil Liberties Union and others. Pittsburgh Public Safety officials said they were trying to protect the public when plainclothes officers arrested a protester at about 5 p.m. Saturday in the city and placed the person in an unmarked, white van. Public Safety officials said the protester had repeatedly refused to work with police and was blocking intersections needed for people to get to hospitals and for students moving into the University of Pittsburgh.