Explosions At Boston Marathon Finish Line
 

In the event that you've been living under a rock for the last 2 hours:

Two Explosions Rock Boston Marathon Finish Line; At Least 2 Dead, 23 Injured

Yeah they keep on showing it over and over again.

No one seems to know what did it or who did it or if it was even a bomb. Now they are saying that the explosion at JFK Library is unrelated.

I'm guessing a tea party bombing, a tax day protest in the place that brought us the concept of "boston tea party".

Based on the look of the explosions, clearly low explosive, probably black powder. With the timing close enough yet far enough apart enough that a single person could have planted them, using kitchen timers, walking casually from one site to the next.

Nice pic of the second explosion.

http://i.imgur.com/3HNLktB.jpg