Understand. But I doubt they were carrying or watching or scanning at all. Condition White (in more than one way). The lady whose service they were working on described the attacker as walking in a way that he could have been flagged (not her words).
I just realized something. Whites are in Condition White. That’s the problem.
http://teddytactical.com/SharpenBladeArticle/4_States%20of%20Awareness.htm