Well 4chan is saying that the shooter's name is John Earnest and his manifesto is a Pastebin file posted at April 27, 2019, 12:10:12 CDT. I don't know if this info is true yet or just a prank on /pol/.
15:34 - 2019 api. 27
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Badirudi kargak luze hartuko duela.
Baliteke Twitterren kapazitatez gaindi egotea edo momentuko gainkarga bat izatea. Berriro saiatu edo Twitterren Egoera ikusi informazio gehiagorako.