Earlier, it was reported that he rented a car at the beginning of the week. This is why I don't believe it was random. I believe he planned this, maybe even went there earlier in the day to try to plant IED's. Just a theory of mine, please don't pounce.
I agree. Facts presented indicate a plan. I wonder if something went wrong for this end result. It appears to me their plan was not fully carried out???? Yet why? IMO