Those fears of terrorism were quickly assuaged, as regional utility company Pepco said the cause was a “voltage issue”—namely a power surge. The Department of Homeland Security said there was “no indication of any malicious activity” involved in the outage.
“Shortly before 1 p.m. Tuesday we experienced a dip in voltage in the Washington, D.C., area. This was caused by an issue with a transmission line. There was never a loss of permanent supply of electricity to customers,” the utility wrote in a statement, adding there aren’t any “current supply problems” and crews are “investigating the cause.”
The outage shut off lights in Metro stations, downtown buildings, traffic signals, and it even trapped people in elevators at the University of Maryland campus in College Park. Some students tweeted that people were stuck in elevators, prompting the local fire department to rescue them. Meanwhile, a photo being circulated on Twitter showed students at the university taking their final exams during the blackout, using their cellphones as lights to complete the test.
White House correspondents onsite said the power went out briefly at the building—causing the lights to dim—before it was switched over to a backup emergency generator. Other federal buildings, including the State Department and Capitol, suffered a power loss. The Smithsonian also said the blackout hit some of its museums and they were promptly evacuated.
The State Department was forced to cut short its daily briefing due to the outage, agency spokeswoman Marie Harf tweeted. Harf did the briefing in the dark, using a phone light to shine on reporters who were asking her questions. She later said power was returned to the building about two hours later.
At the same time, the blackout occurred while Oprah Winfrey was doing a speech to commemorate the new Dr. Maya Angelou stamp from the U.S. Postal Service. According to an onsite WUSA-9 reporter, Winfrey kept going and quoted Angelou’s “Phenomenal Woman” without a microphone.
Utility providers said a fire at an electrical facility in Southern Maryland was the likely source of the outage. SMECO, a customer-owned cooperative that provides electricity in Southern Maryland, said a Pepco “transmission conductor broke free” at its station, which resulted in the outages, but there was no damage done to the equipment.
Pepco’s outage map showed that more than 2,400 customers were without power in Washington, D.C., at one point. D.C. Department of Homeland Security and Emergency Management spokeswoman Robyn Johnson told The Associated Press the outage affected at least 8,000 customers in the city.
Later, White House press secretary Josh Earnest said Homeland Security authorities “do not currently see a nexus to terrorism” related to the outage, reported Voice of America.
But Adm. William Gortney, the head of the U.S. Northern Command, said the outage shows U.S. power grids have “vulnerabilities” to attack. “All of those critical infrastructures are fragile,” he told the news agency.