Murderer? LOL. uh okay.
"Muder - Murder is the unlawful killing, with malice aforethought, of another human, and generally this premeditated state of mind distinguishes murder from other forms of unlawful homicide (such as manslaughter)."
The establishment has an 8-yr old age rule, from what I heard.
The establishment should have had proper guidance and supervision, along with instructors that can recognize if a customer can't perform proper tasks to test-fire a gun.
Parents are not firearm instructors, and brought their kid to a proper range/instructor to get training. There is no harm in that thinking/want. It's actually the more responsible thing to do than to have mr.dad who probably doesn't instruct/train teach the kids. Every kid should understand firearms, and how they react/perform.