Only a nuke could cause this.......and a nuke in DC at that.
EMP would disable MOST military satellites in the line-of-sight and many military comms on the ground......especially if detonated at 30k feet along the eastern seaboard.
COMPLETE CHAOS with very few, if any, deaths resulting from the explosion and radiation. Most would be casualities from the total loss of order, most transportation and almost all electronic communication. Even the electrical grid would fail.
Nope. UnderscoreJim says the grid can't be taken down...