All but the last shot have the same sound pattern - a shot then an echo, the last shot however, did not echo, plainly indicating it was not the shooter but the shot of the sniper. The echoes were the result of being surrounded by hard surfaces (the roof) while the last shot, lacking an echo, was shot from the groun on a grassy area.
We found a video with clear sound here: https://www.theepochtimes.com/epochtv/video-the-moment-shots-are-fired-at-trump-rally-in-butler-pennsylvania-5685824
All but the last shot have the same sound pattern - a shot then an echo, the last shot however, did not echo, plainly indicating it was not the shooter but the shot of the sniper. The echoes were the result of being surrounded by hard surfaces (the roof) while the last shot, lacking an echo, was shot from the groun on a grassy area.