The 5.8-magnitude earthquake that unnerved millions of people on the East Coast of the United States on Tuesday forced schools in three states to close and damaged several buildings and federal landmarks.

At least four aftershocks followed the powerful quake, including a 3.4-magnitude tremblor that hit near the nation's capital overnight.

Capstones fell from three spires on the National Cathedral and cracks appeared in the flying buttresses on the east side. Cracks were also discovered at the very top of the Washington Monument, forcing the National Park Service to close the 555-foot-tall obelisk for "an indefinite period of time." The Old Solders' Home, the Ecuadoran Embassy and at least two high-rise apartment buildings suffered damage, as well.

The startling geological event, which spawned in an unmapped fault near Mineral, Va., about 87 miles southwest of Washington D.C., was the strongest East Coast tremor in 67 years. Although it was not a killer quake, seismic waves were felt as far north as Montreal and as far south as Florida, the US Geological Survey reported.

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