With all these reports of multiple shots fired at several locations with no evidence of shots fired when police arrive on scene - does anybody remember four or five incidents last year at malls and airports where multiple shots were reported fired and no subsequent evidence was found. I thought there sere test runs at the time - how hard would it be to fire-up a bluetooth speaker for a minute or two - Makes it mandatory law enforcement would respond. This attack is clearly not lone wolf. It seems that the shooters had a lot of support.
Proactive caution and panic could also trigger reports of benign activity.