It sounded like an explosion at first to some of the Americans along the East Coast zone where an earthquake rattled the ground beneath them Tuesday.
But the damage wasn't as bad as intially feared.
The Canadian Press has the story:
WASHINGTON -- Stones, tiles and plaster came crashing down from landmarks around Washington, D.C., and a nearby nuclear power plant shut down during Tuesday's surprisingly strong earthquake that rattled buildings over hundreds of miles along the East Coast.
The region's infrastructure and communications networks were tested and generally appeared to have held up well.
The White House said advisers told U.S. President Barack Obama, who is vacationing on Martha's Vineyard, Mass., that there had been no reports of major infrastructure damage.
Still, at least three of the four pinnacles fell from the towering Washington National Cathedral, said the Episcopal landmark's spokesman Richard Weinberg. And a crack was found near the top of the Washington Monument.
Elsewhere around the nation's capital, 90 miles northeast of the quake's epicenter in Virginia, ceiling tiles fell to the floor at Reagan National Airport. The gothic-style Smithsonian Castle, built in 1857, had minor cracks and broken glass, said Smithsonian Secretary Wayne Clough.
And vigorous shaking left a crack and hole in the ceiling at historic Union Station when a chuck of plaster fell near the main entrance. Officials strung up caution tape around a large area of floor.
"We thought an explosion at the Metro had happened. Some rocks started to fall on the floor and people started to panic and run out of the station,'' said Omar Abyed, who manages a shop near that spot.
No damage was reported to power distribution grids.
Right after the quake, cellular telephone networks were overwhelmed with calls with people checking with friends and relatives about whether they felt it. Delays were rampant though they had cleared up later in the afternoon. The Federal Emergency Management Agency asked people to use text messaging or email for a few hours to keep lines open for emergency responders.
Tourists and workers evacuated the Capitol, monuments and memorials. Portions of the White House and Pentagon also were evacuated. Workers streamed out of the World Bank and International Monetary Fund on Pennsylvania Avenue.
Many tourist sites then closed, but no damage was reported to the Washington Monument or Lincoln Memorial.
Buildings in other places across the region, including City Hall in New York, were also evacuated. Still, no significant damage was reported in the city of skyscrapers.
Around Mineral, Va., a small town close to the epicenter, masonry crumbled, and display windows shattered.
Workers poured out of PPL Corp.'s 22-story headquarters building in Allentown, Pa., the city's tallest.
"I've been here 30 years and I've never felt anything like that. It was visibly shaking, things on my walls were shaking, which is a little disconcerting,'' said PPL spokesman Dan McCarthy.
Many workers were allowed to go home early around the region, and numerous buildings were being inspected for damage.
The North Anna nuclear power station, located in the same county as the quake's epicenter, shut its twin reactors. A backup diesel generator failed, but three others were working to keep the reactor cool. Inspectors were checking for possible damage.
Twelve other nuclear sites from Michigan to North Carolina declared what regulators call "unusual events,'' without any reported damage. Inspections were under way at those sites too.
The Tennessee Valley Authority was inspecting 15 dams for damage.
Amtrak passenger trains between Baltimore and Washington were running at reduced speeds, while crews inspected stations and railroad equipment. Washington-region commuter rail services, Virginia Railway Express, and Maryland's MARC train service were interrupted during inspections, and there also were delays once service resumed.
Some airports, including JFK and LaGuardia in New York, were temporarily closed, causing delays for thousands of travellers. A small number of flights were cancelled or temporarily diverted. New York bridges and tunnel stayed open