WASHINGTON (AP) — It's lights out for several government buildings in Washington. Authorities are blaming a blown transformer and a construction mishap.

The State Department says a power line serving its headquarters was severed in a construction accident Monday morning. Emergency generators allowed some staff to keep working, but others were sent to work from different offices or home.

The outage was expected to last for hours. The Pepco power company says it also caused lights to flicker at the White House and other buildings.

Meanwhile, police say a transformer explosion at the U.S. Office of Personnel Management caused outages there and at several government buildings Monday. Those include the Federal Reserve, the General Services Administration, Metro's Smithsonian subway station, the Labor Department, the U.S. Park Police and the Federal Deposit Insurance Corp.