[freeperfromnj]

a foreign terrorist cell, which, to me would conduct these operations simultaneously, in different locales.

Maybe they want to see how this pans out and if they continue to get away with it, will try it elsewhere. This could even be a diversion to focus attention and resources on the suburbs while planning to hit the city

[stuartcr]

Correct, just goes to show how random acts of violence are subject to nothing more than supposition on our part. There are hundreds of maybes, each as valid as the other. If it stops, then we'll never know.

[Sacajaweau]

It looks like they're specifically testing the area AROUND DC proper.

Sac