Evacuees escaping the aftermath of Hurricane Katrina trickled into Texas on Thursday from New Orleans, a city gripped by chaos as looters ran wild, food and water supplies dwindled, and bodies floated in the floodwaters. Even as he pledged vast assistance, President Bush acknowledged, ‘‘This recovery will take years.’’‘‘We know there is a significant number of dead bodies in the water,’’ and others hidden from view in attics and other places, New Orleans mayor Nagin told reporters. Asked how many, he said: ‘‘Minimum, hundreds. Most likely, thousands.’’—an estimate that, if correct, would make it the nation’s deadliest natural disaster since the 1906 San Francisco earthquake and fire, which killed up to 6,000 people.The bulk of the city’s refugees were in or around the Superdome—a shelter of last resort for more than 20,000 people. Governor Kathleen Babineaux Blanco said that conditions there had become desperate, with food, water and other supplies running out, with toilets overflowing. The plans were to move most of the refugees to Houston’s Astrodome, 350 miles away, in a convoy of hundreds of buses. On Thursday, about 3,000 New Orleans evacuees arrived at the Astrodome, which is prepared to accept 25,000 temporary residents, said Gloria Roemer, a spokeswoman for Harris County’s office of homeland security.As survivors struggled with a disaster that left damage of up to $25 billion, a gargantuan relief effort began. Pentagon officials said 30,000 National Guard and active-duty troops would be deployed by this weekend in the largest domestic relief effort by the military in the nation’s history. With police officers and National Guard troops giving priority to saving lives, looters brazenly ripped open gates and ransacked stores for food, clothing, television sets, computers, jewellery and guns, often in full view of helpless law-enforcement officials. Dozens of carjackings, apparently by survivors desperate to escape, were reported, as were a number of shootings.Mayor Nagin ordered 1,500 police officers—most of the city’s force—to turn from search and rescue to stopping the looting.New Orleans, a city of 500,000, mostly below sea level and reliant on levees along the Mississippi River running south of it and Lake Pontchartrain to the north, was a nightmarish waterworld that Nagin said would have to be abandoned while the levees were repaired and the city drained. He called for a ‘‘total evacuation’’, adding: ‘‘We have to. The city will not be functional for two or three months.’’ —NYT