A downed power transmission line in southern Maryland caused a momentary loss of power that led to "widespread outages" in the nation's capital Tuesday afternoon, according to officials.
Previously, District of Columbia emergency management officials had said a reported explosion at a southern Maryland power plant may have been the cause.
A large number of outages were reported throughout the district about 1 p.m., including at the White House, Capitol and State Department headquarters.
According to Sean Kelly, a spokesman for Potomac Electric Power Co., just before 1 p.m., there was a momentary dip in voltage caused by a downed transmission line at a substation in southern Maryland, which is connected to a power plant there.
"The line did come down and it created a flash and some arcing occurred," Kelly said, who declined to call it an explosion. "There was never a loss of permanent electric supply ... but it was enough to trip the backup equipment for some customers."
Some of the outages may have been caused by failure or delay of customers' backup power systems, Kelly said.
White House spokesman Josh Earnest confirmed that the White House was on backup power for a short time, and said Homeland Security officials "do not currently see a nexus to terrorism." The White House was only lightly affected, Earnest said, but elsewhere in the district, that wasn't the case.
State Department spokesman Marie Harf was forced to finish her daily news briefing to reporters in the dark, the Associated Press reports, and the power went out just as Oprah Winfrey was giving a speech to unveil the Maya Angelou postage stamp. Winfrey, true to form, kept going, speaking louder in the dark after the microphone went dead.
The outages also knocked out power at several Smithsonian museums, according to the institution's Twitter account. The buildings were evacuated about 1 p.m.; by 3:15 p.m. power had been restored at all the museums and the buildings had been reopened.
The power had also been restored at the Capitol, according to a tweet from the sergeant at arms of the Senate, and a number of Metro stations, which had been running on emergency power for lighting, regained power by about 2:45 p.m.
Aquita Brown, a spokeswoman for the Metropolitan Police Department, said the outage did not affect 911 service or emergency response agencies.
The University of Maryland also announced it would close early Tuesday because of the outage, the university's president said on Twitter.
FOR THE RECORD
1:22 p.m.: An earlier version of this post mistakenly said the University of Maryland announced it would close early Thursday.