Planes crash into World Trade Center, Pentagon

6:45 p.m.-- Government buildings in Washington have been shut down following apparent terrorist attacks at the Pentagon and at the World Trade Center in New York. All federal office buildings including the White House and U.S. Capitol in Washington have been evacuated and are shut down. Liberal leave is in effect. The Central Intelligence Agency in Langley, Va. has also been evacuated. National landmarks including the Washington Monument, the Statue of Liberty, and St. Louis Gateway Arch have also been closed, according to the National Park Service. Portions of both World Trade Center towers in New York city have collasped since a plane crashed in to one of the towers this morning around 8:45 a.m. A second plane crashed in to the other World Trade Center tower approximately 18 minutes later. At approximately 9:45 a.m. a third plane, an American Airlines Boeing 767, crashed on the helicopter landing pad next to the Pentagon and careened into the building, breaking through three outer rings of one wedge of the Pentagon. While many offices in this section of the Pentagon are empty because of a recent renovation, some Army logistics and planning offices were in the area affected by the crash. At least two dozen Pentagon employees have been transported to area hospitals with injuries, according to CNN. Defense Secretary Rumsfeld and all senior military staff are unharmed. There are no reports on how many people have been killed due to the attacks. At 9:45 a.m., the Federal Aviation Administration closed all air airports in the nation, the first general stop of air traffic in U.S. history. The FAA will not reopen airports until noon Wednesday at the earliest. About 50 airplanes remained in the skies until 1:00 p.m. but have now landed, according to FAA spokesman Les Dorr. Dorr added that twenty-two international flights bound for the United States are still up in the air but would be allowed to land shortly. Speaking at a Florida elementary school this morning, President Bush decried the World Trade Center attack as "an apparent terrorist attack on our country." Bush then boarded Air Force One and later landed at Offut Air Force Base, Neb. Around 6:00 p.m. Bush returned to Washington. "I want to reassure the American people that the full resources of the federal government are working with local authorities to save lives and help the victims of this attack," said Bush aboard Air Force One. "Make no mistake, the United States will hunt down and punish those responsible for these cowardly attacks." Bush added the U.S. military around the world had been placed on high alert. 50,000 people work in the World Trade Center complex including 2,800 federal employees, according to an official with the General Services Administration (GSA). The official would not say if there are any federal offices in the twin towers themselves, but did say that GSA leases two low-rise buildings located about 80 yards from the towers. Agencies with offices in these buildings include the Customs Service, Alcohol, Tobacco and Firearms Bureau, U.S. Secret Service, Equal Employment Opportunity Commission (EEOC), Defense Department, and Internal Revenue Service. These buildings were evacuated following the first attack on the World Trade Center, according to the GSA official. All employees with the Customs Service and EEOC in the World Trade Center were successfully evacuated and are unharmed, according to spokesmen with the agencies. "We do know that our people at the World Trade Center got out safely," said Customs Service Spokesman Kevin Bell. At least one of the two GSA-leased buildings was damaged when the twin towers collapsed in late morning, according to the GSA official. More federal offices are located nearby in New York's Federal Plaza, according to Don Kettl, a scholar with the University of Wisconsin. Federal Plaza was unharmed in the attack, according to an FBI official in the building. Later in the day, Bush counselor Karen Hughes said the federal government had implemented its emergency response plan following the first attack on the World Trade Center. "While some federal buildings have been evacuated for security reasons and to protect our workers, our federal government continues to run effectively," said Hughes. John Randt, a spokesman for the Military Traffic Management Command (MTMC), heard the explosion at the Pentagon from MTMC Command in Virginia. "We were watching the smoke and fire from the first explosion at the world trade center. Some moments later, we heard a distinct KABOOM! A very deep rumble sound of the very largest artillery from my Army days," said Randt. "Then word came it was the Pentagon and I worked there four years and it is absolutely incredible what has occurred at that building. It the nation's oldest office building, solid concrete," he said. According to Randt, all nonessential government employees were told to leave. Witnesses are in "deep shock, deep consternation," he said. The Federal Emergency Management Agency's Urban Search and Rescue Task Forces have been activated for deployment to the World Trade Center in New York City, said Marc Wolfson, a spokesman for FEMA. The task forces are specially trained to search for survivors of bombings. Federal buildings nationwide have been put on heightened security alert, according to the GSA. Agencies in GSA-controlled facilities throughout the country may be closed at the agency's discretion, according to GSA. The multiple terrorist attacks prompted shock and outrage amongst congressional lawmakers. Rep. Curt Weldon, R-Penn., said federal intelligence agencies had failed to provide any advance warning of the attacks. "This is a failure of the nation's intelligence system," said Rep. Curt Weldon, R-Penn, on CNN. "Today our government failed the American people." Tanya N. Ballard, Kellie Lunney, Jason Peckenpaugh, Katy Saldarini, Joshua Dean, Matthew Weinstock, and Katherine McIntire Peters contributed to this article.