President Bush was taping NBC's "Concert for America 2002" when the cell phones and pagers started going off.
His senior advisers, many of whom were at the Monday night taping, were getting chilling news from their deputies: American interests abroad may soon be attacked.
According to officials involved in the deliberations, the first scent of trouble came in the afternoon, when a group of intelligence experts from scores of federal agencies got word that a high-level Al Qaeda operative in custody overseas had warned of plots to target U.S. facilities.
The information jibed with other intelligence available to the group, which meets twice daily by videoconference, at 7 a.m. and 3 p.m.
The officials recalled the days before last year's attacks, when there was a sudden increase in credible intelligence about attacks overseas, and decided to kick the information up the chain of command. It went to the deputies of Bush's senior advisers, who also feared a repeat of last year.
"We just now know a little bit more about what we're looking for than we did on Sept. 11," said one of the officials involved. They all spoke on condition of anonymity.
The deputies reviewed the data and called their bosses, many of whom were with Bush.
Tom Ridge, the president's homeland security director, ducked out of the event to field several calls. At least one other top Bush adviser left the concert to work on the problem.
Later, the advisers met face-to-face and by telephone before settling on a recommendation to Bush: Raise the nationwide alert from code yellow -- a "significant risk" of attack -- to code orange -- a "high risk."
Vice President Dick Cheney, White House chief of staff Andrew Card, FBI Director Robert Mueller, Attorney General John Ashcroft, CIA Director George Tenet and other advisers met twice with Bush on Tuesday morning to discuss their recommendation.
The second session took place in the top-secret Situation Room. "Let's do it," Bush told them.