>>516042251
Thread died while I was creating this image.

>>516041113
Thank you.
I have attempted to map out the area with visible landmarks. Those two people I decided to outline in green are clearly at different levels on that stairway, and are quite near the flash.
I am thinking there is some kind of crawlspace in that area because of the nearby utility box, the pipes above 115H, and those vents.
Even something like a ventilation duct a person may be able to fit inside here prone in some sort of maintenance crawlspace just above the ceiling of the ground floor.

The apparent muzzle flash appears between the concrete beam and the windows. I am seriously wondering if there is a bit of grating for minor ventilation in that gap between the structural beam and windows which could theoretically be removed and provide a firing solution at Charlie?