At first, Richard thinks the approaching people do not hear him...
They simply keep lurching over, as if in a trance.
Sean sees it first, through his vision aides. About half of the people coming closer suddenly start twitching violently as they approach...

Then their heads open up like gory blossoming flowers into strange insectoid stalks of wet flesh, and their necks twist and bend in unnatural ways as if something within is whipping it around. He notices that almost all of them appear to be days old corpses that somehow still amble. What on earth...?!

(OC: Sean, Richard, both of you roll a Fright Check at -2. Roll the same for your NPC companions.)