Vicious ducks. Pecking order help

[kitabubbs]

This has been going on for a while but i have 2 one year old blue sweedish hens that are attacking my 6 month old peckin and kahki camble ducks. I got them seporated and thought it was molting so id be okay in a few week but this morning one of the blues got in and killed one of my 3 week pekins and paralized another?! Am i doing something wrong with their diet? Is it normal? They are scary and chase my dogs too
Update: the two buggers got under the fence (with the help of the dog) and killed 3 chickens and one other baby duck. Help?!