Heart Breaking

"If you have firearms in your home, it is absolutely essential that you ensure -- if you have any locking devices or safe -- that it is properly secured and properly locked,” said Sgt. Spruill. “It does no good to have a lock on a case or lock on a firearm or a gun safe if you don't have it secured from your children."
Officers interviewed the parents and the boy and are investigating whether any laws were indeed broken. However, authorities said that right now they are giving the family time to grieve.
Authorities said the father is an army reservist. Police said no matter a parent's experience with guns, it's important to talk about gun safety with children.

You have to take precautions if you have small children, ether living with or visiting you. Also when they are mature enough, educate them, NRA has Eddie Eagle for younger children, if the child is mature enough take them to the range, do not make the gun a forbidden object. If they want to do grown up things, they have to act grown up, and they need to understand the power of the gun.
Even when you keep a gun for home defense, you have to consider ALL of the safety aspects, ahead of having instant access. There a number of products that allow both security and instant access, and they not that expensive considering what the cost can be.