Five Washington fire trucks responded to the White House and left a short time later, after which employees from the West Wing were allowed back inside.
The Secret Service said the problem appeared to have originated in a mechanical closet and the evacuation was precautionary.
Pool Report # 1 — details of a.m. evacuation of WH
Reporters and photographers were evacuated from the WH just after 7 a.m. Saturday because of a smoke odor. All have now returned to the building — and things are back to normal.
An unidentified White House official told a pool reporter an electrical transformer malfunctioned and set off a smoke alarm.
"The transformer problem was quickly resolved," the official said. "Electricity and personnel access to the West Wing has returned to normal. The first family was unaffected."
CNN said the evacuation seemed to go smoothly and the scene outside was calm as firefighters investigated.