What kinds of Muslims are they? Are they, like some news media was suggesting, members of Al-Qaeda with ties to Iran? That makes sense if you're inept enough to believe that all of Islam is a cohesive whole - the differences between Shi'a (Iran) and Sunni (al-Qaeda) are numerous but, more importantly, they are also incredibly final. Al-Qaeda, much like al-Shabaab, explicitly denounces all non-Sunni Muslims. Are they Pakistani Muslims, Afghans, Somali, Dagestani? Do you know why the difference matters?
And the worthless dog nut pricks who SPECIFICALLY target and MURDER innocent children, women, men or anything else with the intent to create chaos are 99% of the time MUSLIM.