cats afraid after hearing cat fight

My cats heard a cat fight outside last night and have been terrified ever since. They hid under the bed for the rest of the night, and then didn't try and wake me up in the morning for food. I had to coax them to come out and eat. Guinness finally relaxed enough to eat but Nepheline only ate about half of her food. She kept looking up and staring outside and then went back under the bed. She was relaxing a bit more by the time I finally left. Why would it upset them so much? I'm on the third floor of an apartment building so its not like they would have been threatened or anything.

My cats responded the same way when my foster momma got her hackles up and started wailing. Lucky hid behind the couch under the slipcover...took me forever to find her. Try playing some classical or calming music and talking quietly to them. Don't force them out. Pretend like everything is fine, and calm and they will start to come out of it. It too mine a little while, but lots of cuddles when they did come out helped alot.

When she hears stray cats outside the balcony window she gets spooked and runs in a corner and hides, whereas Barkley will get right up in the window to see what all the commotion is about. I just leave her alone and allow her to come back out in her own time and she does eventually resurface, plus I give her lots of love and hugs to reassure her that all is well.