"I didn't know what was happening. I just ran with them," Williams said, adding that "everyone seemed scared. People were crying, people were being consoled and calling loved ones and family."
The impact of the shootings spread through Washington. The Department of Transportation was locked down, as were some U.S. Senate offices, and the Federal Aviation Administration temporarily halted air traffic Monday morning at Reagan National Airport.
Two events Monday night -- a Nationals baseball game against the Atlanta Braves and a Musica Latina event at the White House -- were postponed.
To Brundidge, the encounter with a gunman was hard to believe.
"You know," he said, "you just go to work and you never think something like this is going to happen in your building."