Guessing we will find out that they (the SS) had insufficient manpower and subpar pre-event security planning to go along with poor communication with the locals which led to some confusion and uncertainty in the moments leading up to the shots... Going deeper, while the feds will never admit it, their hiring practices (which may or may not have had an indirect impact in this case) have also likely deteriorated the effectiveness of the SS as a whole (especially in terms of their protection division).