I have been praying for Claire's recovery, but some prayers are not answered.
Karl Pierson, arrived on campus in a state of rage, with a loaded shotgun, and began firing shots down hallways. Allegedly, Pierson was looking to murder a teacher who had him suspended, but couldn't find the teacher, who had fled the school. Claire Davis happened to be in the wrong place at the wrong time, and Pierson shot her instead. She was a target of opportunity. Now that she has died, they can chisel "murderer" into Pierson's epitaph, right next to the word "lunatic."
It appears to me that Pierson was emulating the two killers of Columbine High, intent on killing innocents and setting fire to the school before killing themselves. (In addition to his shotgun, Pierson was carrying three Molotov cocktails in a knapsack. He detonated one in the school library, starting a fire.)
Students from surrounding high schools raised funds for Claire's medical expenses, and the singing group "One Direction" made a video for her. Alas, Claire never got to see it.
Go with God, little lady.
Read more about it here.