The White House briefing room and parts of two US Senate office buildings were briefly evacuated within hours of each other on Tuesday after separate bomb threats, but authorities said it was not clear if the incidents were linked.
In a rare interruption of the White House daily press briefing, reporters were hustled out of the room for about 30 minutes after a bomb threat was phoned in to local police.
The Secret Service and bomb-sniffing dogs searched the premises and eventually gave the all-clear to resume the briefing by White House spokesman Josh Earnest.
President Barack Obama was in the Oval Office, just steps from the briefing room, and was not evacuated, Earnest said. First Lady Michelle Obama and their two daughters were nearby in the White House residence and also were not moved.
The threat phoned in to city police was aimed at the briefing room, the Secret Service said, and that room and the press areas were the only ones evacuated. "It was my understanding that no one else was affected," Earnest said.
The immediate blocks around the White House, including Lafayette Square across Pennsylvania Avenue, were roped off and closed to tourists briefly, a Reuters witness said.
Hours earlier on Tuesday, authorities investigated reports of suspicious packages and a telephoned bomb threat at two US Senate buildings and found nothing hazardous.
US Capitol police cleared a room in the Dirksen building and the courtyard of the Russell building, which houses US senators and their staff near the US Capitol, and found nothing problematic.
"It is an ongoing investigation right now," Secret Service spokesman Brian Leary said when asked if there was a connection between the two incidents.