heard it with my own ears from LE on police scanner!
Maybe it was a prediction.
I have heard a lot of conflicting, contradictory, fog-of-war stuff on the scanner channel. Including the recent gunshots which turned out to be a loading truck. And if the perps truly have access to military-grade weapons, why did they need to build amateur style bombs? I am not disputing at this point that devices resembling grenades might have been used, just that they were actual military grenades.