First let me tell here an Ayat from Quran:
If any one slew a person - unless it be for murder or for spreading mischief in the land - it would be as if he slew the whole humanity: and if any one saved a life, it would be as if he saved the whole humanity.
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Today Death Toll In Karachi Bus Shooting Rises To 44 death and 13 injured
So who are they are these Muslim?
I dont know if they're muslims or not,
but one thing for sure, theyre humans,
and religion is not to be blame for it.