Cop Shoots 11-Year-Old in Chest: Is This POSSIBLY Lawful?

A Mississippi 11-year-old calls 911 saying that his mother's dangerous ex-boyfriend had arrived at their home unexpectedly and was acting aggressively. Cops show up at the house, guns out, and start clearing. The mother exits first, and the a clearing cop starts calling for the boyfriend to come out unarmed. A human form rushes out of a doorway towards the clearing cop, who instantly fires his pistol--striking what turned out to be the 11-year-old 911 caller in the chest. ...