They aren't going to identify her until all of her social media has been scrubbed. This makes me think she's either:
1. Troon
2. Not white
3. Daughter of some prominent politician/uber rich parents(since the area is where rich people live and it was a private school).
As for why she did it, since I'm bored and this is a gossip forum, here's my guesses:
If troon, then obviously mentally unstable and Christian hating SJW. A troon attacking a Christian private school makes sense. It makes even more sense for it to be a troon since Tennessee just passed a bunch of anti-troon laws.
If real woman, then depends on race and politics. If it's a white women, I assume she's some uber woke mentally ill basket case that hates all Republicans, decided to take her anger out on a Christian (and likely Republican) school. If non-white woman, same as above, but also hates white people on top of it.
I could also see this being a real woman who had history at the school or knows someone who worked there, and going in there to kill a specific someone. But then again, the news said she had 3 guns, so it seems kind of weird to bring that many weapons if you're trying to target a specific person.
I'm 50/50 if this is someone local to the area and related to someone prominent. It could be some loon decided to pick one of the richest zip codes to attack, but that also seems kind of doubtful.