CCTV video from what looks like a shooting range shows a man handling a gun with an instructor next to him. For whatever reason, his idea of getting a handle on the gun was by pointing the barrel at the palm of his hand. It didn’t take long for obvious to happen.
I’m not a gun expert, but even I know that two of the most fundamental gun handling rules are never to point the gun at anything you don’t want to shoot, and always treat the gun as if it was loaded. Some people probably need to get hurt to finally get it.