In order to effectively intimidate people in the area, you need to confine the attacks to the area involved. My own expectation is that they will do this again somewhere else--there may be some element of test run in this exercise.
I don't see evidence this is a coordinated attack on an Arts & Crafts chain--its just a coincidence; in the kind of areas where you have the target set up they are looking for, you may have a higher probability of having one of the stores.
It doesn't look to me like any freepers who live outside the area are terrorized--my own view if I lived in the area would be to move on down the middle of the same track on the theory that the odds are on my side.
However to the extent you are denigrating the impact of these incidents, the evidence to the contrary is obvious. I would bet we have between $50 million and $100 million in law enforcement response so far.
More significant in the context of your Reynolds Wrap insult is this--you have an operation which is the exact operation depicted in both the al Queda training manual and an operational training video (in one case the shooting platform is a pickup truck with a canopy; the other is a mini-van I believe); done for exactly the operational purpose; why should we not assume the islamic enemy is the source?
The suicide bomber usually does not get more victims than this crew has; and the bomber does not live to fight another day--he has a 100% casualty rate. You have a wide area population obsessing with this issue; I would bet that there is close to a $100 million law enforcement investment to date. This has been a very successful effort assuming the islamics are in fact the perpetrators.
If this is a terrorist would it be more effective doing a single shot and fleeing...or opening fire on a group of people then fleeing....I would think they would go for the larger group instilling more terror....