A section of the bridge connecting Ocean Springs with Biloxi, Mississippi, wiped out by Hurricane Katrina. (Reuters)

New Orleans, Aug. 31 (Reuters): Overwhelmed authorities struggled to evacuate survivors trapped in the rising floodwaters of New Orleans and to control looters who ran wild today amid the destruction left by Hurricane Katrina.

Engineers tried to plug a leaking levee that was allowing lake water to pour into the city two days after the storm struck the US Gulf Coast.

People left stranded were running out of food and water and growing desperate as authorities tried to determine how to get them out and where to take them.

“We’ve sent buses in. We will be either loading them by boat, helicopter, anything that is necessary,” Louisiana governor Kathleen Blanco told ABC’s Good Morning America. Texas governor Rick Perry said about 23,000 refugees stuck at the New Orleans Superdome arena will be given shelter in the Houston Astrodome.

President George W. Bush’s plane swooped low over three states today, giving him a sombre view of the destruction, as he cut short a vacation in Texas to return to Washington to oversee the US government’s response.

Air Force One descended to less than 900 metres over Louisiana, Mississippi and Alabama to allow Bush to see some of the worst damage.

Two men on a floating door in New Orleans. (Reuters)

Katrina’s death toll was more than 100 and expected to rise much higher, but efforts to count the dead took a back seat to assisting survivors. Rescue teams busy saving people left bodies floating in the high waters.

Looting erupted around the city as people broke into stores to grab supplies, television sets, jewellery, clothes and computers.

“It’s a lot of chaos right now,” Louisiana state police Director H.L. Whitehorn said.

Amid the looting, gun-toting citizens took to the streets in some areas to try to restore order in New Orleans. Where it was still dry, some store owners sat in front of their businesses, guns in hand. One had put up a sign reading: “You loot, I shoot.”

Police said there were dozens of carjackings overnight, by desperate survivors trying to get out of town or obtain supplies.

Somebody fired at a rescue helicopter Tuesday night, forcing its crew to abandon efforts to evacuate patients from a hospital, a state official said.

Authorities were so intent on rescuing flood victims that at first they let the looting go unstopped.

At least 110 people died in Mississippi. “We’re just estimating, but the number could go double or triple from what we’re talking about now,” a civil defence director said.

New Orleans at first appeared to have received a glancing blow from Katrina, but the raging waters of Lake Pontchartrain tore holes in the levees that protect the low-lying city, then slowly filled it up.

The historic French Quarter, the main draw for New Orleans’ huge tourist industry, should escape with only minor flooding.