Philadelphia-area cops seem to have killed an eight-year-old by firing into a crowd. They wounded three others.

Persons in or near that crowd were shooting, sometimes perhaps at the thugs. But if the cops could not identify the shooters and aim carefully at them, they were far more likely to hit bystanders than their targets. What they did may not have been evil, but it was spectacularly incompetent.

Fictional cops know not to shoot at someone in the middle of bystanders. Why didn't these real cops know it?