Following the links so you don't have to (but you should.); from link the first:
The numbers are eye opening. The Justice Department, which keeps all kinds of statistics on violent crime, does not tally up individuals killed annually by police. But by combing public news reports and other sources, the Justice Policy Institute has estimated that police officers in the U.S. killed 587 people in 2012 alone. Over the course of a decade, they’ve tallied more than 5,000 people in the U.S. during that period—far more than the number of people who lost their lives in acts officially classified as terrorism in roughly the same span.