Not sure if description is correct. I got this achievement by hooking 3 players in the basement in one game but not at the same time. I only ever got 2 people on at the same time.
Anyway the easiest way to get this achievement imo, is to go Leatherface and apply the Insidious perk. Once you've got someone hooked in the basement, just camp in the corner and wait for their teammates to come. Using Insidious gets rid of your terror radius after standing still for a few seconds and Leatherfaces' chainsaw can down multiple players. Just be warned, using this method can result in some hatemail for camping, but it's the easiest way to do it.