Why did Zeus kill Asclepius?

Zeus killed Asclepius because he was snatching the dead heading towards the under world to heal them. Hades complained to zeus that he was being robbed by asclepius and so Zeus threw a lighting bolt toward him and it killed both Asclepius and the patient he was tending. I got this from the book heroes,gods, and monsters of the Greek myths by Bernard evslin. I hope this helped. :)