While there are lots of government workers in the DC suburbs (for obvious reasons, probably a higher concentration than you would find anywhere else in the country), so far as I know only one of the seven victims to date worked for the government.
In Israel, very few of the terrorist victims are army or police or anyone associated with the government.
The point of terrorism is precisely to be random, inclusive, and to frighten everyone, especially civilians.
That's what is going on here, IMHO.
It isn't big enough yet to generate certainty that it's Muslim terrorism, but that's what I'd guess it is.
And if it is, its certain to cause a backlash of some significant kind.