The U.S. Capitol building had to go on a generator for a time Tuesday, and Metro trains kept running, but on emergency power. Tourists were evacuated from museums. In the White House, President Barack Obama barely noticed.

All this was spurred by problems at an electrical station 35 miles southeast of Washington that caused widespread power outages Tuesday.

The mechanical failure occurred shortly before 1 p.m. Tuesday at a transfer station in Charles County, Maryland, that is controlled by utilities serving Washington and southern Maryland.

Homeland security officials in Washington and Maryland said there was an explosion at the station, although the two utilities, Pepco and the Southern Maryland Electric Cooperative, could not immediately confirm that there was a blast or fire. No one was injured, the utilities said.

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Associated Press writers Jessica Gresko, Brett Zongker, Amanda Lee Myers and Sagar Meghani contributed to this report.