Some White House staff members were moved out of the West Wing and tourists were rushed from the East Wing and sent to the far side of a park across the street from the compound. Gun-toting Secret Service uniformed officers took up positions around the White House compound.

"There was an indication that an aircraft has entered the no-fly zone," White House press secretary Scott McClellan said. "There's an investigation to determine what it really was."

"There was a report of a possible violation of restricted air space which has since been cleared and closed," said Lorie Lewis, a spokeswoman for the Secret Service.

McClellan said Bush was working in the Oval Office at the time. Bush was taken to the underground bunker. He was there "a very short amount of time," McClellan said.

Cheney was notified about the scare and moved to a secure location, according to an administration official who spoke on condition of anonymity because of the sensitivity of the security information. He arrived at the White House minutes after the situation was resolved.

The last known time Bush was taken to the underground shelter was on the night of the Sept. 11, 2001, attacks when security fears prompted officials to move the president and his wife.

© 2005 The Associated Press

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