The White House press room was briefly evacuated and a Secret Service sniffer dog deployed Tuesday delaying a scheduled briefing.
Journalists, including an AFP reporter, were escorted out as a security sweep was performed.
Outside the executive mansion, the north lawn area was also evacuated as staff and journalists were moved to a neighboring building.
No reason was given for the evacuation, and the reporters were allowed to return to the Brady Briefing Room after the all-clear was given.
Live television footage of the briefing was not immediately halted, and viewers could see a dog handler inspecting the rows of seats.
Later, the camera shots were obscured by material being placed over the lenses.
Earlier, part of a Senate office building on Capitol Hill had also been also evacuated due to a telephoned bomb threat.
Police with dogs investigated a suspicious package but no threat was found and the all-clear was given.