Traffic was blocked off several streets near the White House briefly after a man outside the Treasury Department falsely claimed to be carrying an explosive, the Secret Service said.
No explosive was found and the man was taken into custody for a mental evaluation on Tuesday evening, Secret Service spokeswoman Kim Bruce said.
He was not immediately charged and his identity was withheld pending the outcome of the evaluation.
Bruce said the incident began at 9:45 pm when a man told a uniformed Secret Service officer on 15th Street outside the Treasury, one block east of the White House, that he had an explosive device in his backpack.
The man surrendered the backpack without a struggle, and Metropolitan Police determined there was no explosive in it, Bruce said.
Applying standard security measures, the Ellipse south of the White House, 15th Street between Pennsylvania Avenue and Constitution and E Street between 15th and 17th streets were closed to vehicles and pedestrians until 10:49 pm, Bruce said.