The seal is more of the sort that prevents the opening of something, rather than the animal you are referring to. It was broken, and now evidently pulls people from their appropriate realities and places them here instead.
The demons will likely appear as normal human beings. Apparently using the word 'Christo' will help you to identify them, as I am told they will flinch and their eyes will turn black. I would advise you make your way to [address], as soon as possible. There is a complex there that is protected from demons.
If you are unsure of how to get there I suppose I could retrieve you, if you would like.