Budgie attacked by another budgie, help?!?

I have an aviary with nine budgies, it is more than big enough but today one of the younger ones I noticed had quite a bad head injury. I know it was caused by another budgie, because I found the one that did it and she had blood around her beak. The victim of it has quite a few of the feathers from the crown of her head plucked, and there is a fair amount of blood but not too much I wouldnt say more than about 2-3 drops of it, I have brought her inside and covered the cage with a blanket, what else can I do?