This was a book that I read in about 1998.
The story opens with a scene in a teenager's bedroom, where a friend is sleeping over. There is the sound of breaking glass from downstairs; shortly after, the bedroom door opens, and the friend is run through with a pike and lifted out. The intruders smell of death, and seem to be covered in dead skin. The narrator (a girl if I remember correctly) survives as she is in the shadows. The rest of the family is raped and murdered. It's not actually supernatural, but the gang of killers initially appear to be monsters, or other-worldly.
Thereafter the point of view switches with each chapter between the surviving girl and one of the gang members.
The title of the book was something like "The Longest Night" or "The Long Day". I can't remember the author's name. I think the story takes place over about 24 hours, but am not sure.
I'd love to be able to recall the title and author, and would appreciate any help.