It ain't just kids.
I was at a public (though non supervised) range a couple of months ago. My wife, sister-in-law and two nephews were with me. My wife and Sis-in-law were down range changing targets, while I kept an eye on the boys, and their hands off the guns.
An older gentleman arrived and occupied the next bench. We nodded and smiled at each other and I pointed out that the ladies were down range. He acknowledged that.
A couple of minutes later, as I was going to the car for a water bottle, one of the boys poked me in the arm and pointed at the next bench.
The old gentleman had placed his rifle, pointed downrange, on some rests, and was adjusting it and snuggling down behind his scope. Both boys looked shocked and surprised... as did I.
I went over to him and pointed again at the ladies downrange. He said "Uh-huh, I see them." and snuggled down behind his scope. I said "I'd appreciated it if you left your rifle alone until they come back from downrange." He kind of frowned at me and said, "Well it isn't loaded and the bolt is open."
I was almost stunned into silence!
But I quickly got over it.
"I don't want you pointing your rifle at my wife. And I don't want her to turn around and see a rifle pointing at her! Nobody is to handle a weapon when people downrange." (I had made the assumption earlier, that he would probably know some range basics because he had a couple of veteran's bumper sticker on his car.)
He grudgingly left he bench and went and fumbled in his car for something. In an attempt to ease the tension I suggested this might be a good time for him to set up a target, but he ignored me.
When the ladies came back, the boys told them what had happened. They were not pleased.
When we announced we were ready to shoot again. The old fellow fired a few rounds, then packed up his stuff and left. I don't know what he shot at, because he never went downrange to set up a target himself!
There was a universal feeling of relief when he left, and much discussion about the incident later at the burger joint. The boys were not at all happy about watching someone point a gun at their mother and their aunt.
At the very least they got a memorable lesson about shooting range saftey and responsibilities.