Sans and a couple others went further into. I stayed here to look for clues, but you may catch up to them if you go quickly enough.

[ She slowly goes back to the books. She doesn't think they'll find anyone alive down there, but. Hope is a hell of a drug, isn't it? Then she slowly shake her head, speaking more for herself than anything following Aziraphale's comment. ]

If they're human, they're doing a bad job at being human...