President Barack Obama and his family were not affected by the incident, according to the White House.
U.S. Secret Service spokesman Max Milien said that at about 7 a.m., smoke was seen coming from a mechanical room closet on the first floor.
Journalists and others were evacuated out of "an abundance of caution" and the District of Columbia fire department was called, he said.
People were allowed back into the building about an hour later.
No injuries were reported.