We have learned two things about the early stages of this kind of horrific event, and they ought to be operative here.
First, it is a mistake to get too far out in front of the initial reports, which are almost always wrong in some details — sometimes, in some major details. It is Patriots’ Day, and that could be significant. It is also Tax Day, and that could be significant. And let’s not forget that it’s Monday and we are living in a country that has been the target of hellacious terrorist attacks by jihadists who proclaim that they intend to continue attacking us — any day, any time. Any of those things could be relevant, or maybe none of them will be. We just will not know until investigators get further along in the scut work they have only begun doing.
Second, the government and the media have demonstrated a disturbing tendency to withhold and massage facts in these incidents. Some delay in disclosure is obviously necessary, on the law-enforcement side of things in particular, in order to conduct a competent investigation — you want to capture the culprits, and that becomes much harder to do when information gets publicized that gives conspirators a motive (or I should say, even more of a motive) to flee. But government officials and journalists who are invested in fairy-tale narratives often use the need for reasonable law-enforcement secrecy to stanch the normal flow of information or try to manage it in the service of the narrative — see, e.g., Fort Hood. It is important to press the pertinent officials to give us the facts straight and let us figure out what to make of them.
The recent history of terrorist attacks is that investigators figure out who is responsible within a very short period of time, both because of the high priority such investigations are given and the tendency of terrorists to signal their responsibility for what they’ve done (after all, the point of terrorism is to leave us intimidated by the terrorists, so they obviously feel the need to brag). We will know who did this soon. It is counterproductive to do much speculation.