I picked up an english translation of the Qu'ran yesterday and began reading it. I have a question from The Bakarah 2:54
And recall when (on returning with this favour) Moses said to his people: “My people! You have wronged yourselves by taking the calf for an object of worship, so turn in repentance to your Creator and kill yourselves.This will be best for you in your Creator’s sight.” Thereupon He accepted your repentance. Indeed He is Much-Relenting, Most Compassionate.
My question is that if killing people is haram then why would God allow the Israelites to kill each other for worshipping a false God?