vomit bag, as in someone is spilling the beans...
Or perhaps something to do with a haz-mat, some kind of bag that soaks up spills.
maybe that have the shotgun beans bags for people control like the cops do.
Man, I should have thought of that one
It could be a vacuum splint, they have Styrofoam beads in them, that once air is sucked out becomes hard as a rock.
They feel like a bean bag chair, albeit a small one.
To the best of my knowedge, bean bags used by law enforcement are used to stun the bad guys, (less than lethal force) and they are fired from shotguns. But, since the FD called for them, I don't know what they could be.