That's sad, the parents must be upset.
So much for the beloved freedom to bear arms in America. Look, I don't have a strong view either way, but certainly some parents need to be more responsible and keep guns in locked unaccessible places to children. What an eight-year-old boy was doing at a gun fair, holding an Uzi I'll never know - that's a disgrace and there should certainly be restrictions (e.g. age limits) for those who go to gun fairs and certainly live ammo should not be used. What if that eight-year-old boy had been the very stupid 'white supremacists' arrested in America yesterday? What if they had been 'black supremacists'? Although all hypothetical it is very possible and incidents like this, undermine the right to own arms in America all together.
However an Uzi? I'm pretty sure that the right doesn't extend to that. I don't see the point of the 'Machine Gun Shoot and Firearms Expo'... why would anyone who is not in the military need one?
The arms controls are generally quite good in America in comparison to other countries with where arms are legalised though... This incident is sad though.