I suspected that, but haven't seen it posted. Some of the video of the people shouting the warnings said "Ma'am".
Even if I had to duck to avoid the rifle, I would have reached up to empty a magazine in his general direction.
Firing a shot or two in the air might have been enough. The SS snipers did have the bad guy in their sights. Apparently waiting until he fired or they got the order from above. The shots might have triggered their reaction.
It worked at Kent State.
Shots fired, would have at minimum caused a commotion, would have instantly alerted everyone and the sound and resultant commotion would have turned eyes to it.
Now if it turned out you were engaging a pasty on the roof, it could have also provided a window of attack from another vector.