Chicago Police say that they have arrested five people on Tuesday who were protesting over a video showing a white police officer shooting a black teenager 16 times in Chicago last year.
The video, released on Tuesday, showed the 2014 shooting of Laquan McDonald, 17, by a white police officer. Police say he refused to drop a knife.
Officer Jason Van Dyke has been charged with first-degree murder in the case.
Chicago Mayor Rahm Emanuel has appealed for calm in the city.
Mr Van Dyke has said through his lawyer and police union he had feared for his life.