Seems to me the TWO SURVIVORS are alive ONLY because one of the other victims screamed loudly and scared the murderer off.. Just speculating of course.
I believe they also had coded locks on their privates doors. Can’t confirm.
I heard that the reason they survived was due locking their bedroom door. That is why the killer just past right by them. This is why I lock my bedroom door when I go to sleep. The killer figured if he tried to knock down the door many would wake up.