Fox attack again

Well, we have been under fox attack again. I let my chickens out whilst we were having lunch last Wednesday. We heard a commotion, ran outside and there was a fox with my light sussex chicken in it's mouth. I ran screaming out it and it dropped it and scarpered. It had actually attacked 2 of my chickens, both had puncture wounds in their backs but a trip to the vets and some medicine seems to have set them on the road to recovery- poor things.