"We've been sleeping on the . . . ground like rats," Levy added. "I say burn this whole . . . city down."

With a rag shielding her from the searing midday heat and a cart at her feet holding her only belongings, 70-year-old Nellie Washington hardly saw the troops as heroes.

"What took you so long?" she asked. "I'm extremely happy, but I cannot let it be at that. They did not take the lead to do this. They had to be pushed to do it."

The soldiers' arrival-in-force came amid angry complaints from the mayor and others that the federal government had bungled the relief effort and let people die in the streets for lack of food, water or medicine.

"The people of our city are holding on by a thread," Mayor Ray Nagin warned in a statement to CNN. "Time has run out. Can we survive another night? And who can we depend on? Only God knows." Earlier, in a rambling radio interview, Nagin had erupted in tears and anger.

For his part, Bush said the damage was "worse than imaginable." The president consoled weeping women and praised Coast Guard teams that pulled stranded people from the roofs of flooded homes. In New Orleans, he flew by helicopter to the ruptured 17th Street levee and watched workers load huge sandbags that were airlifted and dropped into the breach.

He stayed far from the worst-hit areas of the city and places that have been gripped by crime. Bush met with state and local officials, including Nagin.

"The president is starting to grasp the magnitude of the situation," said Sen. Mary Landrieu, D-La. Sen. Trent Lott, R-Miss., said, "The president obviously was just stunned" by what he saw.

Early in the day, the military convoy arrived with flatbed trucks pushing axle-deep through the trash-strewn waters carrying huge crates, pallets and bags of relief supplies, including Meals Ready to Eat. Soldiers in fatigues sat in the backs of open-top trucks, their rifles pointing skyward.

"The cavalry is and will continue to arrive," said Lt. Gen. Steven Blum, commander of the National Guard. He said 7,000 Guardsmen would be in the city by today.

Behind the military vehicles came a line of dozens of air-conditioned coaches that began pulling into the Superdome, where a vast crowd of bedraggled people — many of them trapped there since the weekend — stretched around the entire perimeter of the building, waiting for their deliverance from the heat, the filth and the gagging stench inside the stadium.

But another commander warned it may yet be days more before evacuations from the convention center begin because the first priority is bringing in food and water.