An earthquake with a preliminary magnitude of 5.9 struck Tuesday afternoon near Washington, D.C., the U.S. Geological Survey said.

The epicenter was in Mineral, Virginia. The quake was four miles deep, according to the USGS. Did you feel it? Send CNN an iReport.

To get complete coverage and all the latest updates, click on CNN's main story here. View a CNN Open Story about the quake. CNN Open Story combines iReports with reports from CNNers across the globe on a map and timeline.

Update 3:36 p.m. ET: Terminal A at Washington Reagan National Airport has been evacuated because of an odor of gas, airport spokeswoman Courtney Mickalonis said. Initial sweeps of the building showed no major damage from the earthquake.

Light structural damage has been reported in Culpepper and Orange counties in Virginia, said Laura Southard of the state Emergency Operations Center. She said there have been no reports of injuries in Virginia.

Update 3:28 p.m. ET: The White House and adjacent buildings evacuated as a precaution following the earthquake have been given the all-clear, the U.S. Secret Service said. The FBI and Justice Department have also reopened evacuated buildings.

Update 3:25 p.m. ET: East Coast residents should be prepared to feel aftershocks from Tuesday's earthquake, a U.S. Geological Survey official said.

Update 3:22 p.m. ET: The North Anna nuclear power plant, located 20 miles from the epicenter, is shut down and in a safe condition, a company official and the Louisa County public information office report. There has been no release of nuclear material, Louisa County spokeswoman Amanda Reidelbach said.

Update 3:04 p.m. ET: All national monuments and parks in Washington are "stable but closed" following Tuesday's earthquake, a United States Park Police spokesman Sgt. David Schlosser said. A couple of minor injuries and some minor structural damage have been reported in Washington, following Tuesday's earthquake, according to Schlosser.

Part of the central tower of the National Cathedral, the highest point in Washington, was damaged, according to spokesman Richard Weinberg. "It looks like three of the pinnacles have broken off the central tower," Weinberg told CNN.

Update 3:02 p.m. ET: Amtrak is reporting service disruptions between Washington and Baltimore because of the earthquake, the company reported on Twitter.

Aftershocks are a concern, U.S. Geological Survey seismologist Lucy Jones told CNN. "People should be expecting (them), especially over the next hour or two," she said.

The quake was felt in Philadelphia, Pennsylvania; New York City and on Martha's Vineyard, Massachusetts, where President Barack Obama is vacationing. It's unknown if the president felt the quake.

The Pentagon has been evacuated, CNN's Barbara Starr reports. "When the building began shaking rather violently, hundreds of people began streaming out," she said, because many people thought that the building was under attack. Starr was standing in the Pentagon's press office when the roof started to shake.

Cell phone service has been disrupted in New York City, CNN learned within minutes of the quake.

Updated 2:47 p.m. ET: A "considerable amount" of water from a water pipe has flooded two corridors of the Pentagon, according to an announcement in the building. People who work in those areas are being asked to stay in their offices while workers try to repair the damage.

The National Cathedral in Washington is damaged, CNN has confirmed.

And Dominion Generation, which operates the North Anna nuclear power station in central Virginia a few miles from the epicenter of the earthquake, is trying to reach operational staff at the plant, according to a company spokesman. Landlines to the plant appear to be down.

Shortly after the quake struck, traders in the New York Stock Exchange also felt the quake and shouted to each other, "Keep trading!" CNN's business correspondent Alison Kosik reported from the floor at 2:20 p.m. E.T.

Twitter traffic suggests the quake was felt all over the East Coast.

In Philadelphia, HunterPence3 tweeted, "Wow Earthquake just shook the entire locker room!"

In Cleveland, "tribeinsider" wrote "I'm no expert but i think we just had an earthquake here."

And even in Toronto, Canada, tweets said that the shaking could be felt for minutes.

Pete Krech, who works at a business in Fredericksburg, Virginia, likened the sensation to being on a jolting amusement ride. "I was receiving a supply truck," said Krech, store manager at Mattress Warehouse of Fredericksburg, south of Washington. "I felt a vibration under my feet."

Brendan Wein, a sales representative at Hoffman Nursery in Roxboro, North Carolina, said he thought there was a helicopter flying above his work building.  "I was literally shaking in my chair," he said.

CNN iReporter Jeff Yapalater said he was in his backyard in New York's Long Island when the earthquake hit. "Suddenly I felt this light swaying of the Earth. I'd never felt that before, so I thought maybe I was experiencing vertigo for a moment, and it lasted maybe 30 seconds ... We're feeling this really far away!" he wrote.