I expect the Obama admin to attempt to make use of this tragedy, to diffuse the natural reaction most people will have.
This happened in Massachusetts, where firearms are heavily controlled, then escalated in Cambridge, the most liberal place in America. The attack involved recently nationalized citizens, using improvised explosive devices. Anybody with a partially functioning brain is going to predictably respond in a way that counters the desires of the Obama administration.
So, Obama is going to have to thwart it all with a giant P.R. campaign.