They're neither zombies or vampires...both imply that they're dead...they're not dead, they've just been exposed to some sort of virus...they are very much alive, they've just lost their typical human tendencies.
Well, there's also the possibility that he set it himself and forgot about it. I don't think that's true in this movie, although I've heard that's what happens in the book.
They're just not very clear about it, and if you look closely, the details of it aren't really in line with the rest of the movie.
i keep hearing it sucks comared to the book,
Name a movie that was better than the book.
go ahead, I'll wait.