They have NOT really confirmed the use of a vehicle (drive by shootings) and we're assuming that.
Would the sniper have "powder residue on him??". If he was taking the shot from a "ground setup", would there be residue?? Can a dog pick it up??
I know its pushing it but I think the guy is "mostly" on foot.
Is there a college in the circle around the early hits??
Sac
But on foot seems very plausible to me.