It's not the age of the shooter but the intent of the shooter. Any person regardless of their age that intends to do harm to someone with a weapon has to be stopped one way or another. How many times have you see 8 yo children in third world countries carrying and shooting AK's. They are just as deadly as an 21 yo shooter. If it's a young child and depending on the situation my old AF training may kick in...shoot to wound not to kill while in CONUS.
With the way that the world is today and the abundance of "ambulance chasing lawyers", I strongly advise against "shooting to wound". First of all, under stress, a "placed shot" is extremely difficult. Second, it's highly likely that will be argued that if you had time to determine and manage to "shoot to wound", you have adequate time to get away and you didn't feel you were in "real" danger. If you do manage to get off on the criminal trial, then you're still likely gonna face a civil trial where you'll have to deal with some 14 year old in a wheel chair telling his sob story of how he'll never be able to play football with his friends, how he used to be a star basketball player, but now he's gotta play in the wheel chair league, etc. As a firearms instructor, I would strongly advise that if you ever need to shoot a BG in SD, make every effort to "stop the threat" in the quickest and fastest manner possible. If a double tap at "center mass" does the trick, then so be it.
Here's what I would do in the situation.
1. Take cover. Anyone milling around or running away stands a higher risk of gettng shot.
2. Draw my firearm and order the gunman to "drop the gun" (this applies to all BG regardless of age/gender).
3. If the BG fires at me or agresses in any manner, fire my firearm as many times as it takes to "stop" the BG from harming me or others in the vicinity.
4. Call 911 to reort the incident and get medical attention for myself and anyone else who needs it.
5. Clear and secure my firearm.
6. Make no statements about the incident to police. I'll cooperate to the best of my ability but request an attorney before any questioning.
Notice in #3 I say "fire as many times as it takes to "stop" the BG...." This is important to remember, because many folks are killed
because they fired twice, then stopped not realizing that the BG was still able to fight and managed to fight back.
As always, I state "I am not an attorney. This is not legal advice. Consult a competent attorney if you would like legal advice."
Be safe out there, it's a crazy world and unfortunately it ain't getting any better.