The White House briefing room was evacuated on Tuesday in the middle of an afternoon daily briefing with spokesman Josh Earnest after a Secret Service agent came in and instructed everyone to leave.
A Secret Service dog was brought in to sniff around the room.
Reporters were taken to another building on the White House complex.
The North Lawn of the White House complex was also evacuated, CNN reported.
Earlier on Tuesday authorities investigated reports of suspicious packages and a telephoned bomb threat at two US Senate buildings, and found nothing hazardous.