The way I imagined it (sorry if that wasn't described properly) is that she is running, at first, she started from behind that car to the alley, when the dumpshock hit her, and she faltered, had to support herself with the hands. She saw you running after her and while she kept one of her hands to her temple she run two more steps, and that's when you got to her, shot at her. She tried to dodge, tripped, and now she is tumbling in front of you.