Probably the work of a mentally disturbed lone wolf with a troubled past.
Nothing to do with the religion of peace, of course.
Why should we be surprised.
While Europe is rushing ahead to recognize another Muslim failed state, one that does not exist (Paleostine), they are being attacked, in Sydney, London, Paris, Malmo and a host of other European cities...
Wake up.
Sounds like workplace violence committed by a Tea Party type.