I'm speculating from the left wing view here...
It seems to me there may be something more going on here
that sort of smacks of a PR job by the feds.
The feds worked with this 17 yr old kid (student) for 2 years,
made a
real bomb for him to test out in the woods
the test bomb actually
did explode,
but they did not arrest him until some time later,
on a particular night when crowds assembled for a X-tree lighting in the main .
Only one of the local TV stations had the story last night (exclusive ?)
and they had a sheaf of "legal documents" describing the history of the case in detail.
The whole story last night was just too neat and too complete for a first news report.
If it's a real case, I have a second concern about the FBI's decision
to let the (now) 19 yr old park the vehicle in amongst a large crowd,
being absolutely certain he had not substituted their fake bomb with the real thing.
I'm ordinarily not much of a conspiracist, but it seems to me
they should have had sufficient evidence after 2 years working with him
to arrest and charge him without taking such a risk with safety of the public.