Vice President Dick Cheney (search) repeatedly authorized U.S. fighters to shoot down hijacked airliners as the Sept. 11 terrorist attacks unfolded but his orders did not reach military pilots until the last of the four planes had already crashed, the commission investigating the terrorist attacks said Thursday.

Cheney at one pointed believed incorrectly that his orders had resulted in the shoot-down of a couple aircraft.

Click to read the Sept. 11 Commission's report (pdf).

The commission's report documented a day of confusion and miscommunication at the White House, Pentagon, the Federal Aviation Administration (search) and the North American Aerospace Defense Command (search) (NORAD).

President Bush, at an elementary school in Florida to talk about education, was initially told that a small, twin-engine plane had crashed into the World Trade Center in New York. He thought it was a case of pilot error. At the White House, Cheney was wondering "how the hell a plane could hit the World Trade Center" when he saw on television the second aircraft strike the South Tower.

When it became clear that the nation was under attack, Bush decided to continue his remarks to a classroom of second graders. "The president told us his instinct was to project calm, not to have the country see an excited reaction at a moment of crisis." Fifty minutes later, he was on Air Force One as it climbed into the sky with no certain destination. The objective was to get into the air as fast as possible and decide where to go, the commission said.

Cheney, in an underground bunker at the White House, held a series of telephone calls with Bush. He asked Bush to decide the rules of engagement for combat planes being scrambled over Washington. Bush said he authorized that hijacked planes be shot down.