It is unknown how these zombies came to be, but their goal was simply to rest in peace, as they hated being disturbed by anyone. They speak only in groans, which they probably didn't do when they were living.
Role in the film
Jim Evers descends into the mausoleum with his daughter Megan in order to find a key in a dark crypt. Jim opens the crypt and finds the key held clutched in the hands of its occupant. But no sooner does he remove the key than the corpse rises up as a zombie. The undead creature shambles toward the intruders, only for Jim to knock its head off.
Suddenly, the rest of the zombies in the mausoleum awaken, intent on ridding themselves of the living beings inside their tomb. Jim and Megan race back up the stairway, but the door suddenly slams shut in their faces. Jim's son Michael is now the only one who can save them, but large spiders (which Michael dreads) start crawling all over the door, trying to prevent anyone from opening it.
Realizing that rescuing his father and sister is far more important, Michael manages to unlock the door as the zombies are dangerously close to them. The three start to close the door just as one of the zombies reaches its hand out. Putting their backs into it, they shut the door, unintentionally severing the zombie's arm.