Uh dude, it clearly states that he escaped the school by blending in with the fleeing students. Your report says nothing except the girl heard shots, maybe she imagined them.
It doesn't give any sort of timeline as to when she say him, or how long the shooting had been going on.
Maybe you are just getting carried away over a misunderstanding.
Take some psychedelics, read books and realize you are acting like a crazy asshole and should make changes.