University of Maryland also lost power
(DEVELOPING) Scattered power outages hit the State Department, White House, U.S. Capitol and Justice Department Tuesday, news reports said.
There was no immediate information on what caused the outages in some cases confined to only parts of the buildings or when power might be resumed.
Sounds like they lost one leg or 1 phase of the two or three that power the buildings. That would also explain the lack of generator backup.
With all the hot air in DC, you'd think they'd have a convection windmill somewhere to keep the lights bright.