By Alan Elsner
WASHINGTON (Reuters) - Three planes crashed into major U.S. landmarks in New York and Washington on Tuesday, destroying one of New York's mighty twin towers, in a dramatic and deadly attack on the United States.
Loss of life from the attacks was feared to be catastrophic and could number in the hundreds or even thousands.
Both of the twin towers of New York's World Trade Center were struck by planes deliberately plowing into them at the start of the workday. Shortly afterward, a third plane crashed into or near the Pentagon (news - web sites) in Washington, setting off a big fire.
The Pentagon, the White House, the Capitol, the Supreme Court and other key government buildings were evacuated as the nation ground to a virtual halt and panic spread throughout the country. Authorities grounded all planes in the United States, an unprecedented step.
President Bush (news - web sites) called the deliberate aerial assaults an ''apparent terrorist attack,'' and ordered a full-scale investigation.
Early reports said all three planes used in the attacks were hijacked, two of them from Boston. It was not immediately known who flew the planes and what happened to them.
The first plane crashed into one of the twin towers of New York's World Trade Center as thousands of workers arrived to begin their day.
HUGE HOLE IN BUILDING
It opened a huge hole near the top of the building. Two hours later, the building in which thousands of people collapsed on itself in a huge cloud of smoke and fire.
TV stations caught the second plane plowing into the second of the twin towers, exploding in a fire ball a few minutes after the first impact.
"It's clear that this is terrorist-related. We're not sure who is responsible,'' a U.S. official said.
"There was no advance warning of this,'' the official said on condition of anonymity.
One of the planes that crashed into the World Trade Center was American Airlines' Flight 11 from Boston to Los Angeles, said Lori Bassani, spokesperson for American's flight attendants union.
Bassani, who said she was in a meeting with American officials in Fort Worth, Texas, American's headquarters, said if full, the flight on the Boeing 767 would carry 158 passengers. That would include two pilots and nine or 10 flight attendants, she said.
She said she did not know how many people were on board.
Bush cut short a visit to Florida and rushed back to Washington to face the greatest crisis of his young presidency.
"Terrorism against our nation will not stand,'' Bush said before leaving for the capital.
"Today we've had a national tragedy. Two airplanes have crashed into the World Trade Center in an apparent terrorist attack on our country,'' he said, speaking before schoolchildren, teachers and parents at Emma E. Booker Elementary School, where he had planned to talk about education.
"I have spoken to the vice president, to the governor of New York, to the director of the FBI (news - web sites), and have ordered that the full resources of the federal government go to help the victims and the families and to conduct a full scale investigation to hunt down and to find those folks who committed this act,'' said Bush.
He called for a moment of silence. "May God bless the victims, their families and America,'' he said, his voice breaking with emotion.