Fortunately, the brothers who committed the Boston Marathon bombing appear to have been positively identified. One is believed dead, in a shootout with police last night, and the other appears to be trapped in a house in Watertown. Both men, Tamarlan Tsarnaev, and Dzhokhar Tsarnaev are Russian immigrants from Khazakstan, though it is not known if they are radicalized due to Chechen origins, or if they had some other grievances.
I long noted that this act has the stamps of amateurism all over it, and it that would likely turn out to be either foreign terrorists or right-wing extremists. It will remain to be seen what political philosophy these inidividuals follow, but it doesn't particularly matter. The important thing is that the situation will be resolved soon.