NEW ORLEANS — The cavalry finally arrived.

With a cigar-chomping general in front, a camouflage-green convoy of at least 3 dozen troop vehicles and supply trucks rolled through floodwaters Friday into a desperate city where some storm survivors had died waiting for food, water and medicine.

"Thank you Jesus!" Leschia Radford shrieked amid a throng of tens of thousands outside the New Orleans Convention Center.

Some people threw their arms heavenward and others nearly fainted with joy as the trucks and hundreds of soldiers arrived in the punishing midday heat in a scene that looked like a relief mission to a Third World country.

Meanwhile, President Bush took a land and air tour of hard-hit areas of Louisiana, Mississippi and Alabama, and admitted of the relief effort: "The results are not enough."

"What is not working right, we're going to make it right," he pledged during a stop in Mobile, Ala.

Friday offered both the first signs of real hope for recovery and fresh setbacks:

• The day was ushered in with a thunderous explosion before daybreak and scattered downtown building fires that only confirmed the sense that New Orleans was a city in utter collapse. The explosion, at a warehouse along the Mississippi River about 15 blocks from the French Quarter, sent a pillar of acrid gray smoke over the city.

• Congress passed a $10.5 billion disaster aid package, and Bush quickly signed it.

• With Houston's Astrodome already full with 15,000 storm refugees, that city opened two more giant centers to accommodate an additional 10,000. Dallas and San Antonio, as well as the state of Utah, also had agreed to take refugees.

• Tragically, a bus carrying evacuees from the Louisiana Superdome overturned on a Louisiana highway, killing at least one person and injuring many others.

• At the broken levee along Lake Pontchartrain that swamped nearly 80 percent of New Orleans, helicopters dropped 3,000-pound sandbags into the breach, and pilings were being pounded into place to seal off the waters. Engineers also were developing a plan to create new breaches in the levees so that a combination of gravity and pumping would drain the water out of the city, a process that could take weeks.

Even with the arrival of supplies and troops, there was anger and profane jeers from many in the crowd of nearly 20,000 who questioned why they had to wait four days after Hurricane Katrina and threaten to riot before they could get anything to eat or drink.

"They should have been here days ago," said 46-year-old Michael Levy, whose words were echoed by those around him yelling, "Hell, yeah!"