People on the left are saying, "I hope it isn't a leftist". Muslims are saying, "I hope it isn't a Muslim extremist". Tea partiers are saying, "I hope it isn't a right-wing kook". Gun enthusiasts are saying, "At least it wasn't a shooter". Hermits are saying, "There was a bombing? Well, I hope it wasn't the Unabomber".
The fact is, random bombings are an extremist act, a demented act. None of the mainstream members of those groups I just named would want to be associated with such a heinous act. I say that as a tea partier who just wants my government to follow The Constitution and fight corruption.