Further thought

The most obvious candidate for doing the shooting would be the Broward County Sheriff’s office, particularly a member of the SWAT team. What if the whole office was in on this?  What if somebody has promised each of them $1 billion, once they get their polices in place, and independent media trampled underfoot?

Think about it:  The guy does the shooting, hides out somewhere, then comes out once the rest of the SWAT team gets there.  This would explain why none of the other sheriff’s went in.  It might even be the case that the murder weapon was checked out of the SWAT equipment locker.  Hard to believe anyone would check, but it’s possible.

And likewise in Las Vegas: the simplest way to hide other shooters would be to make them cops. Not fake cops: REAL cops, either shooting from concealment, or making sure to kill everyone who saw them. 

Oscar Wilde once commented that life imitates art far more often than art imitates life.  This rough scenario was the gist of the first Odd Thomas novel, just as the idea of flying a plane into a building as a weapon of terror first occurred in Tom Clancy.