Balls of flames and smoke billow out of the top floors of the World Trade Center Towers 11 September 2001 in New York City. Witnesses say two separate planes flew into the towers, in what is suspected to be a terrorist attack.

NEW YORK, Sept 11 (AFP and iviews.com) - Two planes smashed within minutes of each other into the twin towers of New York's landmark World Trade Center on Tuesday and similar attacks were reported near the Pentagon and other major landmarks in Washington.

A witness reported a "sonic boom" as a commercial passenger jet collided into the north tower of the 110-story World Trade Center building between the 80th and 85th floor.  Both of the World Trade Center towers completely collapsed minutes after the crash.

The report said the FBI was investigating at least two possible plane hijackings ahead of the crashes.  In the meantime, the FAA has ordered all outbound flights in airports across the country grounded.

US officials said the crash of two aircraft into the towers of the World Trade Center in New York and in Washington appear to be acts of terrorism. 

"It does appear to be terrorist related," said the official, who asked not to be identified. 

A view of the collapsed World Trade Center

The official said the assessment was based on the action itself, two successive crashes into the twin towers of the World Trade Center within 18 minutes of each other.

At least seven people were injured as two explosions ripped the west side of the Pentagon, forcing authorities to order an evacuation, witnesses said. 

"There was an explosion, a fire. People kept their cool, people started working with each other to get out," said Lieutenant Colonel Robert Snyder, who was in the basement level of the Pentagon building when one of the explosions hit. 

"It's a bomb. Get out," said a Pentagon spokesman as authorities ordered an evacuation of the building. 

Fire trucks were trying to put out the blazes. 

I heard two loud booms -- one large, one small," said Lisa Burgess, a reporter for Stars and Stripes newspaper. 

She said she saw smoke billowing from one side of the building. 

The Pentagon is the country's largest office complex, with more than 24,000 people working within its walls. 

There has been a great deal of speculation as to who may be responsible for the attacks.  But the American Muslim Political Coordination
Council was quick to condemn the apparent terrorist attacks in New York and Washington and offered condolences to the families of those who were killed or injured.

"American Muslims utterly condemn what are apparently vicious and cowardly acts of terrorism against innocent civilians. We join with all Americans in calling for the swift apprehension and punishment of the perpetrators. No political cause could ever be assisted by such immoral acts."

Within minutes another commercial plane ploughed into the south tower, with television footage showing flames and smoke billowing across the New York skyline.

Ira Furman, a former National Transportation Safety Board spokesman, indicated that the crashes were not accidental.

He told CNN there was no indication that normal air traffic would be in the area.

Planes would "normally be clearing the World Trade Center by a few miles," he said.

Meanwhile explosions were reported outside the Pentagon.  

US President George W. Bush vowed Tuesday to launch an all-out hunt for those behind a spate of deadly explosions, as share markets plunged and the world reeled in horror at the carnage. 

Speaking as reports of new explosions and fires around the United States streamed in, Bush said his government would not bow to terrorism and promised the "full resources of the federal government" to hunt down the attackers. 

"Terrorism against our nation will not stand," he said. 

World leaders were quick to join the chorus of condemnation. British Prime Minister Tony Blair said he was "terribly shocked" while French Premier Lionel Jospin said he was "horrified". 

Israel said it was ready to rush aid to the United States "knowing our bitter experience of terrorism," a spokesman for Israeli Prime Minister Ariel Sharon told AFP. 

US Secretary of State Colin Powell meanwhile was seen rushing out of Peru's presidential palace in Lima "visibly disturbed" by the attacks. 

Shares dived -- the German stock market plunged 9.1 percent while trading on the New York stock exchange was suspended. 

The euro meanwhile firmed in response to the crisis while oil prices jumped nearly two dollars in London. 

The World Trade Center consists of two 110-story skyscrapers and are New York's tallest towers. One of the towers is just six feet (two meters) taller than the other.

About 40,000 people work inside the two-building center; more than 150,000 people enter the complex every day for business and pleasure.

On February 26, 1993, a terrorist bomb exploded in building number one's lower level.