Skeleton keeps shooting arrows

Put the summary of the bug you're having here
---Pardon my english----
What I expected to happen was...:
Skeleton stop shooting arrows

What actually happened was...:
I was in my creative world, then I changed the gamemode to normal. There were 2 skeletons, I hit one of them. The one I hit shot the other skeleton, and so they shot each other. When 1 of the 2 skeletons died, the skeleton who alive kept shooting arrows.

Steps to Reproduce:
1. I think it's clear enough by the above explanation, if not tell me