All Guns are Loaded
I've never handled blank ammo, but common sense would dictate it be in some way visually distinct from live ammo. Yes? Please?? If it is visually distinct, did the soldiers with the (allegedly) blank-loaded magazines not check for themselves? Your gun, your responsibility.
But the big question is ... even if you are firing blanks, what in the name of little green apples would possess you to even think of POINTING your weapon at live people you have no intention of making into dead people? Blank ammo can still kill. I am sure there are American military who are curling up into whimpering balls at the mere thought of ever pointing even an empty weapon at civilians. Not as a joke. Not as an exercise. Not even a demonstration with blank ammo. NEVER. What mental giant thought this would be a good thing?
UPDATE: reports coming in that all the live rounds came from one soldier. Who didn't stop when he saw the very realistic blood? Hmmm.