Here is a statement condemning the act from Council on American-Islamic Relations, which says, in part:
No religious or political ideology could ever justify or excuse such wanton and indiscriminate violence. The attack was particularly heinous in that it targeted the all-volunteer army that protects our nation. And it is permissible to lie to the infidel (Sura something-or-other).
This was Sudden Jihad, plain and simple.