An announcement came from the RV.
That blows the theory that this was meant for 630pm.
Also, the perp was looking to minimize human casualties.
The FBI got caught flatfooted, they were clueless about this.
I don't agree with that- It just means that the loudspkr mssg was on the same timer system as the bomb. I seriously doubt that a live person was in the RV doing the loudspeaker and the bomb, unless it was alihu fubar.