Helicopters plucked frantic survivors from rooftops of inundated homes on Tuesday and hundreds were feared dead along the US Gulf Coast after Hurricane Katrina sent a wall of water into Mississippi and flooded New Orleans, Reuters reported.

The economic cost of the hurricane's rampage could be the highest in US history, according to damage estimates.

"The devastation is greater than our worst fears," Louisiana Gov. Kathleen Blanco told a news conference. "It's totally overwhelming."

An overnight breach in New Orleans' protective levee system allowed water from Lake Pontchartrain to flood most of the city.

In the Mississippi coastal city of Biloxi, hundreds may have been killed after being trapped in their homes when a 30-foot (9 meter) storm surge came ashore, a city spokesman said. Cadaver dogs were being brought in to help find the dead.

"It's going to be in the hundreds," spokesman Vincent Creel told Reuters.

New Orleans Mayor Ray Nagin reported bodies floating in the city's floodwaters.

Rescuers struggled through high water and mountains of debris to reach areas devastated by Katrina when it struck the Gulf Coast region on Monday. The storm inflicted catastrophic damage all along the coast as it slammed into Louisiana with 140 mph (224 kph) winds, then swept across Mississippi, Alabama and Tennessee.

It shattered buildings, broke boats, smashed cars, toppled trees and submerged whole neighborhoods. Risk analysts estimated the storm would cost insurers US$26 billion, making Katrina potentially the costliest US natural disaster.

Most of the deaths appear to have been caused by the storm surge, which swept as far as a mile inland in parts of Mississippi.

Hundreds of people climbed onto rooftops to escape the rising water that lapped at the eaves. They used axes, and in at least one case a shotgun, to blast holes in roofs so they could escape through the attics.

Plucked to safety

Police took boats into flood-stricken areas to rescue some of the stranded and others were plucked off rooftops by helicopter. The Coast Guard helped rescue 1,200 in New Orleans on Monday night and thousands more all along the Gulf Coast on Tuesday.

"We've been pulling them off sometimes four at a time, sometimes as many as 12," said Coast Guard Petty Officer Larry Chambers. "People are being taken to the nearest dry spot then the helicopter's going back and picking up more people."

In New Orleans, "We probably have 80 percent of our city under water; with some sections of our city the water is as deep as 20 feet," Nagin told television station WWL. "Both airports are under water."

New Orleans is a bowl-like city mostly below sea level and protected by levees or embankments. The levees gave way overnight in places, including a 200-foot (60 meter) breach that allowed the lake waters to pour into the city center.

The US military planned to use helicopters to drop giant sandbags filled with gravel into the breach in an attempt to fill it.

Pumps failed and floodwaters threatened downtown and the historic French Quarter.

"This is a horror story. I'd rather be reading it somewhere else than living it," said Aaron Broussard, president of New Orleans' Jefferson Parish.

Mark of death

In Mississippi, water swamped the emergency operations center at Hancock County courthouse. The back of the building collapsed and "Thirty-five people swam out of their emergency operations center with life jackets on," Mississippi's Sun Herald newspaper said.

The local hospital appealed for more doctors and nurses to treat the wounded. Hancock County emergency workers went from house to house and put black paint on those where people died, CNN said. They planned to return later to pick up the bodies but did not have enough refrigerated trucks.

In Biloxi, the storm surge destroyed some of the casinos that lined the shore and ripped houses off their foundations. Dazed residents foraged for food and water and looting was widespread, the city spokesman said.

"It was like our tsunami," Creel said.

Fires were allowed to burn themselves out because firefighters had only the small amount of water they carried on their trucks.

Before striking the Gulf Coast, Katrina last week hit southern Florida and killed seven people.

Katrina knocked out electricity to about 2.3 million customers, or nearly 5 million people, in Louisiana, Mississippi, Alabama and Florida, utility companies said. Restoring power could take weeks, they warned.

The storm had swept through oil and gas fields in the Gulf of Mexico, where 20 percent of the nation's energy is produced. At least two drilling rigs were knocked adrift and one in Mobile Bay, Alabama, broke free of its mooring and slammed into a bridge.

US oil prices on Tuesday jumped US$3.65 a barrel to peak at US$70.85 as oil firms assessed damage.

Governors in the stricken states called out more than 7,500 National Guard troops to help police control looting, remove debris and deliver aid.

Convoys of Humvees and military trucks streamed south on Interstate 65 through Alabama with loads of fuel and power generators. Special Forces boat crews were dispatched to conduct search and rescue operations in flooded communities.

The remnants of the storm spun off tornadoes in Georgia and drenched Tennessee and Kentucky. In western Kentucky, heavy rain turn the normally placid North and South Forks of the Little River into torrents and rescuers used boats to retrieve people stranded in a flooded neighborhood. A 10-year-old girl was sucked into a drainage pipe and killed.

(Chinadaily.com via agencies August 31, 2005)