Widespread power outages affected the White House, State Department, Capitol and other sites across Washington and its suburbs as a result of an explosion at a power plant in the adjoining state of Maryland.
Many of the outages were brief in Tuesday's power outages, but others were longer and forced evacuations.
At the White House, backup generators kicked on when the power went out, so the interruption lasted only a few seconds. The complex quickly went back onto regular power. Electricity in the press briefing room dipped around lunchtime, briefly darkening cubicles and blackening TV screens.
"No word yet on whether any official business had been interrupted, but the daily White House briefing was delayed for at least 70 minutes," Al Jazeera's Christopher Sheridan said, reporting from Washington.
An official at the Department of Homeland Security cited by the Reuters news agency said there was no indication of malicious activity behind the power outages.
Reporters in darkness
Power also went out at the State Department during the daily press briefing, forcing spokeswoman Marie Harf to finish her comments to reporters in the dark.
In the Capitol Building, which houses the US Congress, power failure happened twice, and a generator had to be used.
The city's transport operator, Metro, tweeted that several train stations were on backup power. Some traffic lights were out.
DC Department of Homeland Security and Emergency Management spokeswoman Robyn Johnson cited the explosion at the power plant in Charles County, which is run by the Southern Maryland Electric Cooperative, as the possible cause of the outage.
About 8,000 customers in Washington were affected, Johnson said.
Utility company Pepco said it was investigating the issue.
Source: Al Jazeera and agencies