.5% Gaussian blur added some darkening to match the folks in the background.
I'm no longer totally convinced it's fake having looked at it in Shop, the lighter guy in the forground could have been because of the flash...
Could the 'blur' on all the observers be because either they, or the cameraman that took the photo of them, be in motion from the shock of the rifle's retort, while in the original the shooter is more clear and less 'blurred' if he was photgraphed at a different time at a different shutter-speed?