Thank God the kids are ok. It is also a good thing the parents took the time to train their kids safe and proper use of a gun. I have taught each of my kids the safe and proper use of guns. My 12 year old daughter has better trigger safety (finger off the trigger) and muzzle discipline than most of the shooters I see at the range.
These parents probably won't face any charges, nor should they face any charges. They had the foresight, to prepare their kids, for this situation should it ever arise. Good job on the parents part.