Genuinely the place they should have been looking Is at that roof, the one directly behind it (Which appears to be the tallest roof in the immediate area) or the water tower which has clear view of everything except the area to the immediate left of the stage.
Which, why was there no one on the water tower whether as counter sniper or just overwatch (or just to make sure nobody spray painted something mean about trumps sister [small town folks will get that])...