Louisiana, nation responds to shooting death of Alton Sterling _lowres

Jordan Nuerenberg holds up a sign encouraging motorists to honk outside the Triple S convenience store during a rally after Alton Sterling, a black man, was shot and killed Tuesday, in Baton Rouge, La., Wednesday, July 6, 2016. The U.S. Justice Department opened a civil rights investigation Wednesday into the video-recorded police killing of Sterling, who authorities say had a gun as he wrestled with two white officers on the pavement outside a convenience store. (AP Photo/Gerald Herbert)

A federal probe has been launched into the fatal shooting of 37-year-old Alton Sterling by a Baton Rouge police officer. Across the country, celebrities, politicians and others responded to the news of Sterling's death and the graphic footage of it that has circulated online.