I believe the scouts on the top of the hill in the zone in are a group of 5. But the scouts are significantly weaker than any of the other other mobs.
I think more than 5 will come if you don't split. It is easy to pull singles off of that hill. I do it with my rogue until there are 3 left. Rogues can be great pullers in some instances.
if you are not a class that can split . you will get 6 or 7 on that hill at once .. I usually will pull them all then hit my Fade (every class gets a fade (war 10min CD)) then wait for them to roam back up hill and pick off 2 or 3 that stay behind , make sure your close to them or they might try to run back up the hill to bring their friends again.. once you've split them then the rest is PoC (piece of cake)