Is this why (almost) all mass shootings have started out with multiple eyewitness accounts of guys in black (two or more) running around shooting, only to devolve into a single wacked out confused looking kid who is the sole perp?

I recall well the night of the Dallas cop shootings a few years back. I was listening to broadcastify live, hearing the cops yelling out how they were pinned down by crossfire from the tops of buildings. The story kept changing till it was a single guy holed up in a parking garage who was blown up buy a robot bomb. I wasn't surprised.