Attacks hit U.S.

The World Trade Center towers were hit by two separate airplanes on Tuesday morning. Both towers later collapsed.

NEW YORK (CNN) -- Terrorists struck the United States Tuesday morning in harrowing, devastating attacks that included at least three commercial jet crashes into significant buildings.

Hundreds of people are feared hurt or killed. More than 10,000 rescue personnel rushed to the scene.

In the first attack, a plane hit the north tower of the World Trade Center in Manhattan shortly before 9 a.m., followed by another plane into the second tower about 20 minutes later. Both towers later collapsed.

Normally, more than 150,000 people are present at the World Trade Center on an average day. One New York Police official said, "It is like a war zone."

About an hour later, a plane crashed into the Pentagon building, part of which later collapsed. There was extensive damage to the Army corridor of the building. All 24,000 employees were evacuated.

President Bush called the crashes "apparent terrorist attacks" and "a national tragedy." Later in the day, Bush issued a statement from Barksdale AFB near Shreveport, Louisiana. "Make no mistake: The United States will hunt down and punish those responsible for these cowardly acts." Click here for his full statement.

The Pentagon in Washington suffered a major fire and explosion.

Air traffic halted, buildings evacuated

American Airlines told CNN that it lost two planes, both en route to Los Angeles. American Flight 11 from Boston with 81 passengers and 11 crew aboard was lost. This is believed, but not confirmed, to have been one of the planes that crashed into one of the World Trade Center towers. American Flight 77 from Washington Dulles airport to Los Angeles with 58 passengers and six crew is unaccounted for. The jet that crashed into the Pentagon may have been this one, but that is not confirmed.

United Airlines lost two planes: United Airlines Flight 93 airliner headed from Newark, New Jersey, to San Francisco, crashed near Somerset, Pennsylvania. United confirmed the crash of Flight 175 from Boston to Los Angeles with 56 passengers and seven crew aboard. It's possible, but not confirmed, that this is the second plane that hit the World Trade Center. Click here for a map of the crashes.

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The Federal Aviation Administration closed all airports nationwide -- the first time in U.S. history that air traffic nationwide has been halted. No planes were allowed to take off. Planes in the air were being allowed to land.

Normally, 4,000 planes would be in the air across the United States, said FAA spokesman William Shumann.

Bush calls for a moment of silence following the reports of attacks in New York City and Washington.

All inbound transatlantic flights were being diverted to Canada, the FAA said.

The Pentagon, the White House, the State Department, the Justice Department, the Capitol, the CIA and all other government buildings in Washington are evacuated.

Major businesses and stock exchanges were evacuated. Exchange operators said trading would be called off for the day. All tunnels and bridges into and out of the city were shut down. The United Nations was evacuated as a precaution.