The event of last night is certainly to be condemned. However what we must keep in mind in our interpretation of perpetrators is how clear it is what agency they act for. Through endless media-assimilations the truth accretion has become so modified that the doubt-script legitimately runs riot. Many Narps who do not consider themselves particularly counter culture will have found themselves feeling guilty for considering the possibility that this was not a terrorist attack by an external agency but in fact by government Narps (the electoral timing being the key criterion).
This writing does not tell you that it was government Narps, but it does point out that epistemically we really do not know and will not know who committed this; the event hovers exactly in the realm of the agnostic disjunction. These disjunctions display a high degree of incoherence in ability to differentiate between the options (modus tollens remains unfulfilled). Events such as this are often subsumed by conventional agency explanations, this one is no different as such except (as was mentioned above) the timing of it makes it look like it could have been a piece of state-accretion action.
The only determining factors for a claim to be made of actual being of the event are the agencies that try to claim the region (for themselves or others). There exists of course the notion that some Narps can account for it properly, this is not the issue, the issue is that even if these Narps are then put into the medium of passing this truth on, they immediately become subject to the doubt-script that infects the whole system.
Though as a last aside the date for which its media appearance is timed is a little suspicious too.