Fortunately, nobody was hurt. And the explosion wasn’t that large. That area is covered with security cameras, so you know they’re going to find the guy. Probably some nut.
Of course, the rightwing blogosphere are all acting like junior CSI-ers:
From the choice of target, lack of shrapnel, and low amount of explosives used, I think it only logical to conclude that the blast was political in nature, a violent though purposefully less-lethal bomb, if you can ever call an improvised explosive device "less lethal." For these reasons, I doubt it was the act of Islamic extremists.
This was an act of domestic terrorism.
The internet Encyclopedia Browns. What a joke.