This is an unbelievable tragedy, for all of them. She just turned 18, I wonder what her sentence will be like. I assume that in the US - unlike the situation over here in Europe - there is no special "juvenile justice" for young adults, so she might face multiple lifetimes in prison after being convicted for murder.
If I remember correctly you can get separate sentences for each victim, which will sum up to your total sentence.
It's a tragedy for the victims and their families, but I'm sorry, I can't feel sorry for her. Seems she planned to harm them for petty reasons because she feels entitled. Probably a narcissist:
When adult justice is applied, then there’s nothing “juvenile” in that. I guess the thinking behind that (over here) is that you are not yet a fully developed adult when you are 18 and that you might get another chance in life than when committing crimes at older ages.
I believe the point is that there's a process for deciding whether a juvenile should be charged as a juvenile or as an adult. It means a juvenile who is mature enough to be making cold, calculated decisions (like, "hey, I'm a juvenile, I can get away with more") can still be tried as an adult.