Yes, it is possible, mostly. But sometimes they stuck so wierd so you are not able to jump, shoot and free them without any damage. You have to clear the the spot with your sheriff's body and you lose health. I have screenshots if you like to see it.
So would it not better when die aliens don't get traped in this web substance as you named it. Basically they do not stuck in. Makes not much sense to me.
Maybe it is possible to change this behavior in a future update.