Depends on how successfully they can suppress word of the events. If it's like the WTC bombing, then about a week. If like TWA Flight 800, then potentially forever.
The wheels are starting to come off their story here so hopefully they cannot bury this one forever. I remember that first WTC and until last week I didn't realize it was a Ryder truck either.
Until a week ago, I could not have imagined being so close to a bomb that went off and then being told move on it was nothing. Now I know how people feel that are in the area. At least we were in the open -- I cannot imagine being in a building and have that happen.