Widespread Power Outage Plunges DC Into Darkness

A power outage caused by failed utility equipment in Southern Maryland knocked out power across Washington, D.C., with reports of outages at the White House, State Department, several museums, the University of Maryland campus as well as some Washington Metro stations.

The outage was caused by equipment failure at a substation feeding into a Southern Maryland power plant, according to utility providers and US homeland security officials. There are no indications that cyber-intrusion or sabotage is responsible for the incident.

According to Joe Slater, President and CEO of Southern Maryland Electric Cooperative, which operates the powerplant in Charles County, Maryland, a Potomac Electric Power Company line feeding to their facility failed and fell to the ground.

A spokesperson for the utility company, PEPCO, said crews were on the scene investigating the failure of the PEPCO equipment. He did not confirm that the failed line fell.

An official with the Department of Homeland Security official told ABC News that initial information showed the cause of the outage was an explosion in a southern Maryland power plant.

A spokesperson for the Potomac Electric Power Company said the utility company was in the process of restoring generating capacity.

Several Smithsonian museums reported outages and were evacuated. According to the Smithsonian, the buildings will be reopened when power is restored.

The outage knocked out power during the State Department's daily briefing.

The White House experienced a power outage as well, but power came back within seconds. The West Wing is now using a back-up generator.

The power also went out at the Warner Theatre during Oprah Winfrey's remarks at the Maya Angelou stamp event.

ABC News' Jack Date, John Parkinson, Alex Mallin, Mary Bruce and George Sanchez contributed to this report.