One of our cats started being aggressive toward the other cat after it was spayed, need advice

Hi there. I have a question. We have 2 female cats - one older, and one younger (was adopted like half a year ago). They used to get along very well, played together, and groomed each other, no signs of aggression at all. However, 2 days ago we took the younger cat to the vet for spaying (the older one was spayed already). Today we released the younger cat from her enclosure, and to our surprise, the older cat violently attacked her. We broke up the fight and locked two cats in two different rooms. The younger cat is calm, however, the older cat is circling near the door screaming and scratching the door etc. Will this aggressive behavior somehow subside with time? Is that due to medical products used on younger cat?