After reading a bit more, I found witness accounts that he was playing the Brit Arthur Brown’s “Fire” during the attack. This masterpiece was recorded decades ago and I remember listening to it on FM radio in San Diego when I was on active duty in 1968. This incident certainly smells of professional planning.
It’s a terrible narrative. It points out the need for self-defense and the futility of gun laws. This is especially true if the accounts of a Muslim firing back him are true.