Now tell me CarolC if them as did the killing were such devout Muslims and their book, which I believe they reckon is the only book, specifically instructs and commands them not to kill, how come all those people died?

Same reason, I reckon, that people get killed by Christians and Jews and Hindus who believe their interpretations of their holy texts are the right ones. And such killings do take place. The assassination of Yitzhak Rabin is an example of one such killing.