Sad if that kid died but every such story I've ever had sufficent data on to make a reasonable accessment of it revels it was either totally untrue OR there was no such accident as described.
The short article has no info on rifle or handgun other than a .22, nor who was with the kid. "Falling" on a hangun and killing yourself is virtually impossible, even for a nimble kid. Falling on a rife that would be as near as long as the kid is even less likely, at least not in such a way as to cause his own death. Just try to visualize how it could happen, I can't. Well, other than "magic" perhaps.
My money says an accompanying adult loosed the fatal round. Few, if any, five year olds are out alone with a firearm, that just doesn't happen! But they are out with adults, many of whom who are incompetant with firearms.
