so sorry , hope you can find out what happen.
i had a fox last year taking one hen out at a time .the beast came out in the middle of the day. i was sitting guard on the hens free rangeing. when wam! the rotton thing grab a bird .i yelled some adjectives and maybe a pronoun or two , and it let the bird go. she lived later to be called braveheart .shortly after the fox hit the dirt. not by me i add but by a car
hope what ever got your flock meets with the same car!