Parts of the White House and a Senate office building were evacuated on Tuesday after telephone bomb threats.
The White House press briefing room was evacuated just a few hours after parts of the Senate's Dirksen office building were emptied by security guards.
No threats were found at the US congressional complex, and an "all clear" has been declared at the White House.
It is not clear if the two incidents are connected.
The live televised White House briefing was in progress when security agents asked attendees to leave the building.

Upon resuming the briefing, White House Press Secretary Josh Earnest said a bomb threat was made against the briefing room in a phone call made to the Washington Metropolitan Police Department.

A Secret Service spokesman said the evacuation was "limited to the White House Briefing Room and does not affect any other sections of the White House".

Cameras were left running after the evacuation and agents could be seen directing bomb-sniffing dogs through the room.
Earlier on Tuesday, a bomb threat was placed against parts of the US Capitol Complex in a call made to the US Capitol police.
The threat prompted authorities to evacuate parts of the Dirksen office building and to investigate a suspicious package in one of its rooms.

During the same incident, authorities investigated a suspicious package that was found in the Russell office building's courtyard, but that building was not evacuated. The package was later determined to be a left-behind lunch cooler.
Nothing hazardous was found at either location, a Capitol Police spokeswoman said.

A spokesman for the US Secret Service would not immediately rule out that the threats at the Capitol complex and the White House were connected.


Obama, family not evacuated during White House briefing room threat

President Barack Obama remained in the Oval Office and his wife and children remained in the White House residence on Tuesday when the White House briefing room was evacuated because of a bomb threat, spokesman Josh Earnest said in a statement, Reuters reported.
The briefing room is steps away from the Oval Office and very close to the executive mansion where the first family lives, it said.