There was an active shooter drill (or “workshop”) scheduled for Saturday…all too suspicious.
https://www-m.cnn.com/2019/06/01/us/virginia-beach-police-saturday-mass-shooting-workshop-trnd/index.html
…also, one of the employees over there said he thought it was a drill.
https://www.wral.com/co-worker-says-he-thought-virginia-beach-gunman-was-part-of-routine-drill/18425293/