Battle Royale

I don't know what got into Molly and Lucy.  They are normally BFF's and are totally inseparable.  In winter they snuggle up together and when it's warmer they just sleep far enough away from each other to keep cool.  But something happened on Sunday night and I have no clue what started it.  Now it's like I have two former BFF junior high school mean girls and lots of drama.
Molly was outside most of Sunday.  I was sort of worried since it was actually cold, rainy and windy, and I had heard coyotes nearby recently. When she did come in she was kind of bedraggled and nervous.  She made her way over to the kitchen and Lucy ran over to greet her.  Molly was sort of nervous and not her usual self.  I looked away and the next thing I knew they were violently fighting.  We got them separated, but I wasn't able to catch Lucy and put her in another room. When Molly came out Lucy chased her upstairs and cornered her under the bed.  Molly was completely freaked out.  I kept them separated that night, and the last two days.
Molly has been less spooked each day, and is starting to seem normal except for her interactions with Lucy.  That is getting better, but more slowly.  Lucy misses Molly, and cries outside the door of Molly's room.  She seems hurt and worried when Molly growls at her, but she chased Molly under the couch tonight.  Fortunately, Molly was calm once Lucy had gone back outside.  The next time I looked over, Lucy was on the outside and Molly was on the inside, and Lucy had brought Molly a dead chipmunk.