The US President has returned to Washington where he is to address the nation on the series of terrorist attacks in the United States later today. President George W Bush had earlier flown from Florida to Nebraska "as a security precaution".
Meanwhile, a Pentagon official has said that an explosion in the Afghanistan capital was not a US strike. A spokesman for President George W Bush said: "We have no knowledge of who is responsible for the attacks in Afghanistan, but the United States is not".
There is a slight possibility that the attack may be connected with the on going civil war. Television pictures have shown flames illuminating the Kabul skyline. Multiple explosions and gunfire have been heard.
A US official earlier claimed that people with links to the Saudi dissident Osama bin Laden were responsible for the apparent terrorist attacks on the World Trade Building and the Pentagon.
However, Afghanistan's ruling Taliban has denied his involvement. Speaking at a news conference the Afghanistan militia ambassador to Pakistan condemned the attacks.
The Taliban has repeatedly refused to extradite bin Laden to the United States. The US launched an attack on his base in 1998 following bombings of US embassies in Africa, which it is believed he masterminded. Several of bin Laden's alleged followers are expected to be sentenced in New York next week for the embassy attacks.
It is now believed that at least 266 air passengers and crew have been killed in today's apparent terrorist attacks. Four Boeing commercial airliners were hijacked and used to crash into the World Trade Centre in New York and the Pentagon in Washington. A fourth plane crashed in Pittsburg.
Jim Moran, a Democratic member of the US House of Representatives, said that the New York death toll alone is expected to reach 10,000. Mr Moran was speaking on Fox television. According to New York mayor Rudy Giuliani the death toll may not be known until tomorrow. He added that it will be "more than any of us can bear".
American Airlines has said that two of its planes were used in the attacks. Flight 11, a Boeing 767, was en route from Boston to Los Angeles. It had 92 people on board, including staff. Flight 77, a Boeing 757, from Washington Dulles Airport to Los Angeles had 64 people on board, including staff.
The Federal Aviation Administration has confirmed that four passenger flights, two American Airlines and two United Airlines planes are missing. They are all thought to have been used in the attacks.
Security measures around the world have been tightened as a result of the attacks. Both of the World Trade Centre's twin towers collapsed following an attack on the building earlier today. A third building collapsed later.
Two hijacked planes crashed into the twin towers of the New York landmark. The numbers of fatalities are as yet unknown, it could run into thousands. The second ploughed into the southern tower about ten minutes after the first crashed into the north tower. The planes hit at about 9am local time.
The Pentagon was attacked by a third hijacked plane. There were also reports that a car bomb had exploded outside the US State Department, however there is no evidence of this. An AFP reporter leaving the building heard two explosions. It is now thought that the sound came from the Pentagon, which is across the river.
United Airlines flight 93 en route from Newark to San Francisco crashed near Pittsburg. It is believed that 45 people were on board. Speaking to RTÉ News, US journalist Roger McKoy said that a 911 call was made from the plane before it crashed. The caller said that the plane had been hijacked. This is the biggest peace-time attack on the United States.
Transatlantic flights bound for the US were diverted to Canada. All airports in New York and Washington have also been closed. All plane departures have been cancelled in the US in a "national groundstop" order. This is the first such order in US history.
The Federal Bureau of Investigation is on a state of "high alert" following the attacks. The FBI has deployed investigators across the United States and is co-ordinating with US security and police. "The FBI is dispatching full investigative teams to each site. The preliminary focus is at the injured at the scenes," an FBI spokesperson said.
An anonymous caller claimed responsibility on behalf of the Japanese Red Army militant group for the attacks. The caller made the call to the Al-Whaed newspaper.
Editor Fakhri Kawar, speaking to the AFP news agency, reported that the caller said the attacks were carried out to avenge the dead of Hiroshima and Nagasaki. More than 200,000 people were killed when the US dropped a nuclear bomb on Hiroshima on 6 August 1945. Nagasaki was bombed three days later.
Thick black smoke was billowing from the north building of the twin towers and debris was raining on the area as a second plane crashed into the southern tower about two thirds of the way up the building. US President George W Bush has said that the crashes appear to be an act of terrorism.
There is confusion over who is responsible for the attack. An official from a Palestinian group has denied that they are responsible for the attack. Abu Dhabi television had reported that the Palestinian Democratic Front for the Liberation of Palestine claimed responsibility. The Popular Front for the Liberation of Palestine has denied any involvement in the attack.
The Pentagon has also been attacked. The White House, the US Treasury Department and the US State Department have all been evacuated following the attacks. Staff in the UN headquarters building in New York have also been evacuated.
A witness reported a "sonic boom" as a "commercial passenger jet" collided into the 110-storey building between the 80th and 85th floor. Television footage is showing smoke and flames billowing from both building.
About 50,000 people work in the twin towers, in downtown Manhattan; more than 150,000 people enter the complex every day for business and pleasure. On 26 February, 1993, a terrorist bomb exploded in building number one's lower level.
The Department of Foreign Affairs in Ireland has launched two help lines for concerned relatives. They are now operating. The numbers are: 1800 401 800 / 1800 385 858. Two new lines have also been added 1 800 715 165 and 1 800 715 159
The American consulate in Belfast has said that the number for those concerned about relatives from both the North and the Republic is 001 202 646 2500.
