According to news reports the weapon being used by the 8 year boy was a micro Uzi.
http://uk.youtube.com/watch?v=0k6y8VOjOhcJudging from this video the weapon appears to have has a nasty tendacy to pull up even when an adult is using the weapon. If the stock isn't correctly deployed or the stock slips from the shoulder due to recoil then I suspect this weapon would easily rotate especially in the hands of a child.
The father was apparently 10 feet away attempting to take some photographs or video. Youtube is full of videos showing very young children firing extremely powerful weapons.
http://uk.youtube.com/watch?v=sgioghA1QEc&feature=relatedAnd yes there are videos of very young children firing full automatic Uzi's while the photographer is in the front right quarter taking the video

.
http://uk.youtube.com/watch?v=s6BV8P0nNas&feature=relatedSo I guess this type of story doesn't really surprise me.