Credit to Gawker for unearthing the post — read more here.
Luckily, nobody was killed (though two were injured) and the shooter is now in custody. But the post is chilling reminder of the intense media awareness that is now part of mass shooters' horrible calculations.
Also notable, if the post was really made by the shooter: the use of meme-derived language, which was popularized by 4chan, to talk about suicide.