The suspicious package was thrown over the fence about 5:20 p.m. and a section of Pennsylvania Avenue near the White House was closed while it was examined
The U.S. Secret Service said it first used a robot to inspect the bag before having an agent in a bomb suit take a closer look.
After about an hour, it was determined the unidentified bag did not pose a safety risk. No further details were provided.
There were reports that a man was taken into custody at the scene, but the Secret Service did not immediately confirm it.