The terror attacks that hit lower Manhattan yesterday morning spread quickly to the nation's capital, striking at the heart of the US military and plunging the city into stunned chaos.
About an hour after the first of two aircraft crashed into the World Trade Centre, a plane slammed into the west side of the Pentagon, triggering a huge explosion and fire. "It was just a tremendous vibration that went through the whole building," said Ulas Branch, a contract computer programmer who was working at the building. "It was like a sonic boom."
As clouds of smoke billowed upward and emergency vehicles rushed to the scene, federal authorities quickly ordered virtually every government installation in the city evacuated, including the Capitol, State Department, Supreme Court and the west wing of the White House.
They also ordered all aircraft throughout the US to be grounded and diverted all transatlantic flights into the country to Canada.
A long line of fire trucks pulled up and parked along the south-west side of the White House complex. Secret Service and police personnel sealed off the complex and turned away anyone who tried to enter, including high-ranking officials such as Ms Mary Matalin, a senior aide to Vice President Dick Cheney. Ms Matalin later found an official who escorted her inside.
Many private office buildings in downtown Washington were also emptied of workers. Traffic came to a virtual standstill and people milled about in bewilderment on sidewalks, trying with uncertain success to reach friends or family on cell phones.
President Bush cut short a trip to Florida after vowing "to hunt down and find those folks who committed this act. Terrorism against our nation will not stand". Mr Bush made the statement at an elementary school in Sarasota, Florida, where he had gone to promote his education and reading initiatives. He was reading to children in a classroom when his chief of staff, Mr Andrew Card, whispered in his ear around 20 minutes after the first plane hit the World Trade Centre. About half an hour later, a sombre-looking President emerged before the cameras to make his statement and then departed.
The explosion at the Pentagon was so powerful it blasted open windows that were painted shut, witnesses said. "It took your breath away," said Ms Jill Dougherty, a data analyst. "It went right through you. I didn't hear anything. I just felt it." One eyewitness, State Department employee Mr Ken Ford, said he watched from the 15th floor of the State Department annex, just across the Potomac River from the Pentagon.
"We were watching the airport" through binoculars, Mr Ford said, referring to Reagan National Airport, a short distance away. "The plane was a two-engine turbo prop that flew up the river from National. Then it turned back toward the Pentagon. We thought it had been waved off and then it hit the building."
Two other witnesses, Mr Daniel McAdams and his wife, Cynthia, said they were sitting in their kitchen drinking coffee in their third-floor condominium in Arlington just two miles from the Pentagon when they heard a plane fly directly overhead around 9:45 a.m. It was unusually loud and unusually low.
Seconds later, they heard a big boom and felt the doors and windows of their three-storey building shake. From their window, they could see a plume of black smoke coming from the Pentagon.