CHICAGO — On an idyllic summer morning, from a rooftop high above the Highland Park Independence Day parade, a gunman aimed down at the floats and lawn chairs and strollers and opened fire. Members of the high school marching band sprinted for their lives, still carrying their flutes and saxophones. Bystanders scooped up young children and fled. In all, six people were killed and some two dozen others were injured, either by rifle fire or in the stampede away from the scene. The victims ranged in age from 8 to 85. It was the Fourth of July, and the affluent Chicago suburb of Highland Park beca…
