The entire second floor of the Tenleytown Library shook for 40 or 50 seconds and the computers rattled as an the earthquake of preliminary magnitude 5.8 hit the Washington, DC, area, and shock waves were felt up and down the East Coast. 

Some computer users remained at their machines typing away, but this writer scurried quickly down the stairs to the front door where one of the staffers said "it's an earthquake." 

We then got into the minivan and heard a report within three minutes on WTOP radio reporting that the epicenter was at Mineral, VA.

At the Headliner Hair Salon across the street from Politics & Prose, one jar fell off the shelf but otherwise there was little impact.

The Turkish proprietors were sure at the outset that it was an earthquake. (Turkey tends to get more earthquakes than does Washington, DC.) Ditto at Politics & Prose. 

"Only one book fell off our shelves," said a woman at the checkout desk next to the cafe in the basement. 

At the CVS next door, everyone there reported feeling the shock. One man in the drug store said he had been driving from Georgetown when it happened and said his car "shook quite violently" for as long as 30 seconds. 

Metro is reporting that all trains are moving at 15 miles per hour, and personnel are conducting track inspections of the entire rail system.

At the Chevy Chase Supermarket, only about 10 items fell off of the shelves, reported Kevin Kirsch, one of the supermarket's owners, on Facebook. 

Everyone was okay, and the "cupcakes still look good," Kirsch added.