ideally i would be 4 blocks away and still moving.
if it happened, formed around me, unlikely as i very much avoid crowds, i would be moving to an edge with the most avenue of perceived clearance.
but i am thinking more as in a tourist area and the street scene gets ugly.
as you have posted examples of events occurring in fringe/bad areas and after sun down; the answer is--its a free country but one can get hurt expressing their right to be somewhere
ahead of how smart it is to be exercising that right at that moment in that place.
so my answer goes to avoidance 1st, 2nd and 3rd....even if required the use of violance is a poor 4th