Crack Army troops moved to secure New Orleans Sunday after the evacuation of hurricane survivors shifted into top gear, leaving a flooded city of rotting bodies that have yet to be counted.
The city's last two major refuges, where tens of thousands took shelter as Hurricane Katrina approached, were finally cleared on Saturday of the last dishevelled refugees who had endured nearly a week trapped in squalor and fear.
But officials said an unknown number of survivors remained elsewhere having opted to ride out the storm and its aftermath in their own homes.
"There are still people emerging as the water begins to recede, looking for help, looking for rescue," Homeland Security Secretary Michael Chertoff told reporters.
With recriminations mounting over the government response to the disaster, President George W. Bush ordered 7,000 active duty troops to the affected Gulf Coast region.
The first batch of 3,000 soldiers dispatched from the elite 82nd Airborne Division entered New Orleans on Saturday.
Their arrival coincided with a massive air and bus evacuation that finally emptied the Superdome stadium and convention center -- two shelters that became notorious for the killings, rapes and robberies of those who flocked there for protection before Katrina hit on Monday.
Specialist SWAT intervention teams were also standing by as officials pledged to crack down hard on the armed gangs who held the city hostage in the storm's aftermath.
"The streets of New Orleans belong to its citizens, not the violent thugs who have stuck their heads out of holes in an attempt to exploit a national tragedy," said the U.S. Attorney for New Orleans, Jim Letten.
A reminder of the dangers of the past week came with a sniper who started firing near the Superdome as refugees waited to board buses to take them to the New Orleans international airport.
Some 10,000 survivors were flown out of the airport on Saturday to cities across the southern United States in what Transport Secretary Norman Mineta described as the largest airlift in U.S. history.
Following the collapse of the city's medical infrastructure, one airport terminal was turned into a makeshift but large-scale triage unit, supplied with critically or injured patients by helicopters flying in at a rate of 10 per minute.
The scene in the terminal resembled an overflowing casualty ward, with the sick and injured laid out on stretchers, mattresses and even the baggage carousels.
As the flood waters slowly receded, bodies still lay in the streets of New Orleans. The corpse of a black woman remained in a wheelchair outside the Superdome for a fourth day.
No toll for the tragedy was available, but a senator has said the number of dead could top 10,000 in Louisiana. Mississippi has provided a provisional death toll of 147.
Federal Emergency Management Agency (FEMA) coordinator Michael Brown said relief workers in New Orleans, where the stench of urine, excrement and garbage was overpowering, had opened a mortuary in preparation for the grisly task of collecting decaying corpses.
Along the coast at Biloxi in Mississippi, authorities emptied a refugee shelter because of fears of a case of dysentery.
"Our priorities are clear," Bush said in a rare live radio address as he and his administration came under intense fire for their handling of the rescue operation.
"We will complete the evacuation as quickly and safely as possible. We will not let criminals prey on the vulnerable and we will not allow bureaucracy to get in the way of saving lives," he said.
The administration's performance over the past week will quickly come under scrutiny when a Senate committee starts hearings into the disaster response. Bush toured the hurricane-devastated region on Friday and is to return on Monday.
In a sign of things to come, Louisiana Senator Mary Landrieu branded Bush's first visit to New Orleans as nothing more than a presidential photo-op.
"The good and decent people of southeast Louisiana and the Gulf Coast -- black and white, rich and poor, young and old -- deserve far better from their national government," Landrieu said.
The recriminations extended to National Guard troopers who New Orleans deputy police commander W.S. Riley accused of sitting around playing cards while people died in the stricken city.
"For 72 hours this police department and the fire department and handful of citizens were alone rescuing people," he told AFP. "We have people who died while the National Guard sat and played cards."
National Guard commander, Lieutenant General Steven Blum, said the reservist force had been slow to move personnel into New Orleans because it did not anticipate the collapse of the city's police force.
But he described any suggestion that his troopers had not performed well or were late as a "low blow".
Chertoff also offered explanations for the pace of the government's response, saying that hurricane Katrina and the breaching of New Orleans' levees had packed the combined force of an "atomic bomb" that nobody could have predicted.
"That perfect storm combination of catastrophes exceeded the foresight of the planners and maybe anybody's foresight," he said.