In one of the videos from the scene it sounds like there is gunfire from the area of the debris. I have not seen the video, only read reports.
I have been a news photographer for many years. It’s not uncommon to hear what sounds like gunfire at the scene of a structure or vehicle fire. If there is a ammunition in area of the fire it will certainly get hot enough to set it off. I’ve been a scenes where a car fire set off a hundred or more rounds of ammunition. Very dangerous!
I would not surprised to learn there were several people on that plane that were armed. It looked like a pretty hot fire and any rounds in the fire could easily be set off.
Mighty strange, though, that the ammunition went off right after someone yelled, “Shoot!” And then “Shoot again!”
It was very hard to make out anything but the gunfire in my opinion. As I was viewing it I was thinking someone could say almost anything was happening.