Disgruntled or pyscho ex-employee?
I would not be surprised if the killer new the victims and those at the TV station.
He is reported as Vester Flannigan but looks like his real name is Bryce Williams. Looks like this dude maybe tweeting. If you scroll you can see one of his tweets is about him suing the TV Station for Racism.
https://twitter.com/bryce_williams7