NEW YORK — On his first visit to ground zero just days after the Sept. 11 attacks, President Bush climbed onto a burnt-out fire engine and, surrounded in the rubble by weary, stricken rescue workers, vowed vengeance through a bullhorn.

Returning Sunday on the eve of the fifth anniversary, Bush chose grim silence, the company of only his entourage and a few reporters, and floating floral wreaths to remember the attacks that claimed nearly 3,000 lives and transformed his presidency.

Bush and his wife, Laura, made a slow procession into the heart of ground zero, walking four or five stories down on a ramp lined with a flag-bearing honor guard of firefighters and policemen. They were accompanied by New York Gov. George Pataki, New York Mayor Michael Bloomberg, and Rudy Giuliani, who was New York mayor at the time of the attacks.

Reaching the floor of the cavernous pit, now a construction site instead of a recovery mission, the Bushes walked on alone, hand-in-hand and with only the sound of wailing bagpipes in the background. They set wreaths adrift in two reflecting pools marking the spots where each of the twin towers of the World Trade Center once soared

It was the start of a two-day fifth-anniversary tour that will take Bush to all three sites of devastation.

Afterward, the Bushes attended a service of prayer and remembrance at nearby St. Paul's Chapel, greeted firefighters at a firehouse overlooking ground zero and toured a private museum next door that is dedicated to 9/11 families.

"Laura and I approach tomorrow with a heavy heart. It's hard not to think about people who lost their lives on Sept. 11th, 2001," a tight-faced Bush told reporters outside the firehouse, which was destroyed in the attack and rebuilt. "I just wish there were some way we could make them whole."

Bush also called today's anniversary "a day of renewing resolve."

"I vowed that I'm never going to forget the lessons of that day," he said, still clutching his wife's hand. "There is still an enemy out there who would like to inflict the same kind of damage again."

Today, he was to hold moments of silence, to mark the times when the towers were hit, alongside firefighters and other first responders at a firehouse in lower Manhattan; attend a ceremony at the field in Shanksville, Pa., where one of the hijacked planes hurtled to the ground; and participate in a wreath-laying ceremony at the Pentagon. As at ground zero, Bush did not plan to participate in the official anniversary observances at the other crash sites, intending to avoid the distraction that accompanies a presidential appearance.

He is to end today with a prime-time address from the Oval Office.