A Turkish national and doctoral student at Tufts University has been detained by U.S. Department of Homeland Security agents without explanation, her lawyer said Wednesday. Rumeysa Ozturk, 30, had just left her home in Somerville on Tuesday night when she was stopped, lawyer Mahsa Khanbabai said in a petition filed in Boston federal court. Video obtained by The Associated Press appears to show six people, their faces covered, taking away Ozturk’s phone as she yells and is handcuffed. “We’re the police,” members of the group are heard saying in the video. A man is heard asking, “Why are you hiding...