WASHINGTON — President George W. Bush didn't react for five to seven minutes after learning a second aircraft had hit New York's World Trade Center on Sept. 11, 2001, because he was trying to "project strength and calm," a national commission investigating the attacks said.

At 9:05 a.m. on that day, Bush was in a second-grade classroom at the Emma E. Booker Elementary School in Sarasota, Florida, for an event designed to prod Congress to pass his education proposals. Bush had been told that one plane, possibly a commercial jet, had hit the South Tower 19 minutes earlier.

In a moment captured on video and replayed, White House Chief of Staff Andrew Card whispered in Bush's ear, saying, "A second plane hit the second tower. America is under attack." Bush's face froze, his lips tight.

"The president told us his instinct was to project calm, not to have the country see an excited reaction at a moment of crisis," the Sept. 11 commission said in a staff statement issued in Washington today at the panel's last public hearing before it issues a final report next month.

The U.S. government and its military, on perpetual alert for attacks from overseas, weren't trained or prepared to respond to the suicide hijackings in domestic airspace, the commission said in a report giving the timeline of the attacks and the responses of the Federal Aviation Administration and the North American Aerospace Defense Command.

At 8:55 a.m. on Sept. 11, nine minutes after the first airliner slammed into the trade center, National Security Adviser Condoleezza Rice told Bush that a plane, either a multiengine craft or a commercial jet, had struck the center.

"That's all we know right now, Mr. President," Rice said on a secure telephone from Washington, according to the commission report. The FAA and NORAD already knew the first plane had been hijacked and a second was missing, the panel said.

Reporters traveling with Bush's motorcade to the school overheard a voice on a Secret Service agent's radio saying Rice had an urgent call for the president and would be waiting on a secure line that White House staff had set up inside the school.

Behind a blue-curtained partition next to the classroom where Bush would speak to second-graders, the White House had set up a work area with secure telephone lines.

Reporters peered around that partition into the work area and saw White House Communications Director Dan Bartlett on the telephone, his face pale. What he was saying was inaudible.

Behind Bartlett, with his back to reporters, Bush was on a telephone for several minutes with Card standing next to him. After the call, Bush conferred briefly with Card before nodding to White House aides to go ahead and begin the school event.

For the next five to seven minutes Bush went through the prearranged event, greeting students, smiling and asking them about their reading habits. He sat on a small chair, his knees pulled up in front of his chest, looking somewhat distracted.

"Bush made the right decision in remaining calm, in not rushing out of the classroom," said Lee Hamilton, vice chairman of the Sept. 11 commission and a former Democratic congressman from Indiana.

At one point the president got up to tousle the hair of a student and leaned up against the edge of a table. He nodded as the students went through their reading exercises, saying, "That's good, that's good."

Card came forward and whispered in Bush's ear delivering his message. "I told the president, 'The second tower has been hit. America is under attack,"' Card told reporters later.

"When they learned a second plane had struck the World Trade Center, nearly everyone in the White House told us they immediately knew it was not an accident," the commission staff reported.

Bush hurried to finish the school event, thanking the students for the time and encouraging them to keep working. He made no mention of the education bill or Congress's need to pass it. Instead he stepped behind the blue partition to talk with Card and others.

Reporters were prevented from looking behind the partition by White House advance staff. The commission report says the president's traveling staff focused on organizing his return to Washington.

The president's motorcade left the school at about 9:35 a.m. and arrived at the airport between 9:42 and 9:45 a.m.

On Air Force One at about 9:45 a.m., Bush told Vice President Dick Cheney by telephone, "Sounds like we have a minor war going on here, I heard about the Pentagon. We're at war. Somebody's going to pay," the report says, citing notes of the call.