A thermobaric bomb has fuel and possibly oxidizer dispersed in the air, and this cloud is then ignited creating an explosion.

This is how I understood it, but understood "dug in" as "trenches"

smother the personnel.

They obviously tried to avoid casualties by audio with warnings, so that can't be a motive here.

I said in the other comment they could be using the thermobsric explanation to cover for a bomb planted in the interior.

That's a good comment, but it ruins the narrative that a state actor was at work.

Thanks for respect for a larp!