Uzi's are meant to be be shoulder fires, using either a non-collapseable wooden stock or a metal one that can. It can also be fired without the stock, either not engaging the metal collapseable one or removing the wood standard one. The uzi is very "heavy" vs the size/power of the 9mm round it fires. Muzzle climb normally isn't a problem, its heavy enough that the uzi gently rocks rather than climbs. Without any of us being there we will never know why this tragedy occured. I have supervised over 2 dozen machine gun shoots for Florida Ammo Traders when the previous owner still had his class 2 licence. I have braced many an inexperienced shooter. Either placing my foot behind theirs, hand on back or one hand on hip standing close with an arm ready to grab a raising barrel. Always had a mechanics heat glove to protect from the heat of the weapon, luckily never had to grab an errant barrel.
And yes, I've had 8 to 12 year olds fire our uzi's as its the only "safe" machine gun we owned for a younger, weaker person to control, that we were comfortable with. Look at some of the news reels and you'll see children in Africa and the Middle East with AK-47's, full auto. A true tragedy at the least. My sympathies go out to the dad and brother who had to witness this and deal with it. As well as the others there that day.

-Bill Liptak