I am increasingly suspecting that all of this is just a large-scale test area for the Randall Corp's bio-weapons and that at least initially, this may have been just a test.
Still, the fact that they are obviously not coming to help even for their personnel is off.
Also, the footprints definitely hint towards what other people here have already been suspecting: she didn't get infected recently, because it's been a while since she last left the building. Which means she has successfully staved off the infection for quite a while, but ultimately succumbed to it.
Bad, bad news for Kurumi.