Protesters have been marching through Chicago after the release of a dashcam video showing police shooting dead a black teenager.
A white officer was charged yesterday with the murder of Laquan McDonald in October 2014.
The 17-year-old was shot 16 times.
A judge ordered the video's release.
The city's mayor Rahm Emanuel has said his family have urged people to demonstrate responsibly: “They have asked for calm, and for those who choose to speak out to do it peacefully.
“They said they did not want violence to be resorted in Laquan’s name, but let his legacy be better than that.”