What do you mean they weren't the target? Just in the way were they? So who wasn't in the way that day? McVeigh planted a bomb in a building where men, women and children were congregated. You think he gave a damn? He was a callous thug, a cold hearted killer. He didn't give a sh!t who he killed. He did it with a cold heart and was totally callous and unrepentant about it later.
Besides this- there are literally an unknowable number of child killers walking around our country and others as we speak. Some Americans do apparantly get off on killing kids. It is totally preposterous to say an American wouldn't kill a child on purpose- happens all the time.