When I talked to Oklahoma Wildlife, they told me that there are hundreds if not thousands of Red Foxes in the metro area. They don't normally try to trap them, as they are normally fearful of people, domestic cats and dogs, and aren't in large enough numbers to be a nuisance.
The wildlife guy said that the foxes in the area normally feed on rodents, and might get a rabbit from time to time, but that rabbits have better senses of sight, smell, and hearing, and can take evasive action before the fox is even in the yard. He also said most rabbits can outrun a fox, but that it's possible the fox may have captured the rabbit.
In short, if I want the fox captured and relocated I have to hire a licensed contractor to do it, which he said can be expensive because they relocate the foxes pretty far away.
I'm going to wait a few more days and see if the two missing rabbits show back up. I'm doubtful that they will, but the wildlife guy said it's possible they may be nearby, but haven't returned to my yard yet. He said normally they don't stray very far from where they're born.
Thanks for all the kind thoughts, it's nice to know that there are so many who appreciate and respect the animals who live around us. I know we all have a place in this world, but sometimes it's difficult to accept how cruel the world can be, especially when something like a sweet bunny can't be left alone to live its life in peace.
The fox can have all the rodents it wants, if it will just leave the bunnies in the area alone!