In a video statement Thursday, Kansas City Police Chief Stacey Graves addressed the death of Tyre Nichols and the five police officers who were charged in his death, calling it a "tragedy."Nichols died three days after a confrontation with Memphis police officers Tadarrius Bean, Demetrius Haley, Desmond Mills, Jr., Emmitt Martin III and Justin Smith. All five were charged Thursday with second-degree murder and other crimes. "We must reinforce a culture of accountability of the police department from the top down," Graves said. "This is a tragedy. It should not have happened." Graves said she would "do everything in my power to make sure this does not happen in Kansas City." Full video statement below: