This is a cab driver on ground level as it unfolds.
https://www.youtube.com/watch?v=VO92rCrP8hQ&feature=youtu.be
What you here there are multiple echoes coming off of various structures in the area. The change in loudness occurs when he switches back and forth between windows and gun mounts. These windows were not on the same plain. And the gun would be angled differently also. But one can definitely conclude that he intended for people to think it was multiple shooters. A lot of planning here.