A section of the Pentagon in Washington has collapsed following an air attack on the building earlier today. American Airlines has said that one of their planes was used in the attack. Flight 77, a Boeing 757, from Washington Dulles to Los Angeles, had 64 people on board, including staff.
At least seven people were killed on the ground in the two bomb explosions that ripped through the Pentagon. The explosions occurred when an aircraft crashed next to the building. Five floors of the building are reported to have collapsed.
Rear Admiral Craig Quigley said that the Pentagon is under a high state of alert. "We know there are a large number of injured but we have no sense of scale at all," he added.
No organisation has yet claimed responsibility for the attacks. "We are taking every step possible right now to determine who is responsible," a Defence Department spokeswoman said.
US officials and eyewitnesses said that the explosion threw people off their feet inside the building and set off a massive fire. One eyewitness said that the plane appeared to be an airliner.
Officials said that an airliner appeared to have crashed near the helicopter landing site outside the huge building, which is the headquarters of the US military and the office of Secretary of Defence Donald Rumsfeld.
Lisa Burgess, a reporter for the Army newspaper Stars and Stripes, said she was walking in a corridor near the blast site and was thrown to the ground by the force of the blast. Sirens wailed as the whole building was evacuated.
All plane departures have been halted in the United States under a "national groundstop" order, the Federal Aviation Administration said.
The Pentagon is the largest office complex in the United States. More than 24,000 people work in the Washington building.
