That press conference was a shambles.
Lots of talking with nothing being said. First the governor spoke about the tragedy in general terms, then the mayor spoke about the tragedy in general terms, then the senator (?!) assured us that the president (?!?!) is deeply engaged, then the FBI SAIC told us how they're going to investigate (you know, once they get around to it), then the guy from ATF told us how the explosives expert is going to be there, eventually.
It is talking that they hope you take as communication. It is information theater.
Why are they not sharing information? There are three possible reasons:
1. You can't be trusted with information. You might be a bomber, too, for all we know.
2. They don't have information. There are no leads, no clues. They don't know where to begin.
3. They don't like the implications of the information they have. It needs to be massaged before it's just released. It would be great if the bomber turned out to be a race volunteer, because then we can just call it an incident of workplace violence.
None of those reasons is comforting.
NB: the "Al Qaeda" label is a stand-in for "terrorism."