According to the reports, an eight year old kid was trying to fire an automatic weapon, but he lost control of it with one bullet striking and killing him. A fully automatic weapon generates a lot of recoil energy and requires a strong grip. This accident could have been avoided if an adult had been holding onto him, but it's certainly tragic and teaches us that children need supervision when doing something like this.
One unfortunate consequence of these tragedies is that lawmakers scramble to make new laws which they think will prevent these occurrences. Never mind that this accident was fluke. It's entirely possible that an accident exactly like this one has never happened before.
The most remarkable statement about it was found in Criminal Charges Possible in Boy's Gun Show Uzi Death in which the Hampden County District Attorney William Bennett is reported to have said the following:
"At this point in the investigation I have found no lawful authority which allows an 8-year-old to possess or fire a machine gun," Bennett said in a statement.
Surely the District Attorney knows that a law can prohibit certain activities, but if the law is silent then those activities are legal.
There's a constant threat of new regulations on gun shows. So let's make an important distinction. The accident in Massachusetts appeared to have occurred at a facility which offers customers the opportunity to fire fully automatic weapons. That's not a gun show. Here's one example of the confusion. Freakonomics has posted an article titled Are Gun Shows Dangerous?. In spite of that obvious error, the article does helpfully point to an interesting study titled The Effect of Gun Shows on Gun-Related Deaths: Evidence From California and Texas PDF which according to the abstract, maintains that:
We find no evidence that gun shows lead to substantial increases in either gun homicides or suicides. In addition, tighter regulation of gun shows does not appear to reduce the number of firearms-related deaths.
Lesson learned: hold onto a child who is shooting a fully automatic weapon. Here's a video titled Teaching little kids to shoot a sub machine gun showing an adult strictly supervising a youngster learning how to handle an automatic weapon.