The "janitor" moved up to the firing line, training his handgun on the advancing mob, and opened fire with the others. It took perhaps a minute or so of sustained fire, but eventually the last of the creatures collapsed to the floor in a twitching heap. Of course, it was a bit hard to tell at this distance who scored how many kills. But at least the attack had been stopped, and with at least a good 150 metres left between you and the creatures.
"Well, that was refreshing..." Bob muttered under his breath, reloading his sidearm once again. It didn't seem like a working man's sidearm, though - non-metal frame, laser sight, sound baffle... the weapon was definitely a higher grade. The "janitor" didn't seem to make much of a big deal about it, though, and promptly holstered it again.