What happened to my rabbit!?

Its ear is like mangled!! The bottom half is. It is with 3 other adult female rabbits. One of the the rabbits got out last night, but I put her away. It wasn't her though. Anyways these rabbits get along pretty good. Once in awhile they will have a little squabble, but only some hair loss and nipped ears. The ears are never like this though!!! There is fur in the cage, but not her color. I have another rabbit that is unharmed. I can't find the other 2. They are probably in these hue holes they have dug. Could a cat have attacked it? Also, the rabbit that was attacked is not harmed anywhere else!! THANKS!