There was no one behind the building shooting into it. That's government disinformation. The so-called 'flashes' on the FLIR are reflections of sunlight off the broken glass.
Why would the government say “We had guys out behind the building machine-gunning it” to cover up something else?
I didn’t get that from a government story - I got it from the FLIR video.
If you believe that sunlight reflecting off broken glass doesn’t reflect at all, then reflects suddenly in a regular pattern of flashes, then stops for a while then starts up and repeats again, they you’re exceptionally gullible.