New Orleans Orders 3m to Flee As Hurricane Nears

Authorities in New Orleans yesterday took the unprecedented step of ordering the evacuation of the city in anticipation of the arrival of the biggest storm in its history.

The 3 million residents were told to flee as Hurricane Katrina, bringing winds of 175mph and threatening catastrophic flooding, blew in from the Gulf of Mexico.

Roads out of the city were gridlocked and the airport swamped as families tried to reach higher ground. Emergency management officials warned that there could be "massive loss of life" if the hurricane's expected 20ft storm surge breaches the city's flood defences.

"This is the real deal. Anyone who can get out should go now," the city's mayor, Ray Nagin, warned.

Katrina, which claimed nine lives in Florida last week as a much weaker storm, gained strength significantly at the weekend as it headed north across the Gulf of Mexico towards the Louisiana coastline. It was expected to make landfall early today as only the fourth hurricane of category five intensity to strike the US mainland. The last was Hurricane Andrew, which hit Florida in 1992.

The biggest danger to life was from floodwaters; they could reach up to 20ft in the downtown area of New Orleans, which is six feet below sea level and surrounded by the Gulf of Mexico, Lake Pontchartain and the Mississippi river.

Flood defences built after Hurricane Betsey in 1965, a storm that killed 61 and left New Orleans under seven feet of water for weeks, would be unable to withstand the onslaught of a direct hit from Katrina, experts warned. "Within a 10-hour period, the entire metropolitan area could be totally devastated, gone," said Walter Maestri, one of the city's emergency managers.

"We are telling everyone to go," said Kathleen Blanco, the Louisiana governor. "The storm surge could bring in 15 to 20 feet of water, and they will not survive that."

President George Bush yesterday declared Louisiana a state of emergency before the storm arrived, allowing more than 4,000 national guards to take up positions where they would be best placed for recovery efforts.

The declaration also freed federal funds for the cleanup operation, which is expected to last weeks and will cost billions of dollars. Ed Rappaport, deputy director of the National Hurricane Centre in Miami, said that if Katrina maintained its intensity, it would be the strongest storm ever to hit New Orleans. Betsey struck with winds up to 130mph, but Katrina's winds could reach 190mph in gusts.

"We're expecting extensive to potentially catastrophic damage," he said. "Perhaps a million trees will come down.

"The first risk will be the storm surge of more than 20ft along the coast. People must get away from the coast now. We also expect major hurricane conditions across the New Orleans area, and to the east and west. Historically, most lives lost have been because of the storm surge. That's what we're worried about on this occasion."

New Orleans was built in the 19th century on reclaimed swampland and any rain in excess of an inch frequently causes some flooding in the city. Weather experts say that Katrina could bring 20 inches of rain.

Up to 3 million people live in the city's metropolitan area, many more than in the 1960s when Betsey hit, followed four years later by Hurricane Camille, a category five storm that came ashore further along the coast but killed more than 250 people in Mississippi, Alabama and Louisiana.

Michael Brown, director of the Federal Emergency Management Agency, said the population growth meant the storm danger was much greater than 40 years ago.

Despite the evacuation order, more than 100,000 residents are expected to remain in the city. Hotels will remain open for tourists who cannot escape, while the Louisiana Superdome has been pressed into service as a shelter of last resort, according to the mayor. "It will fill up quickly and not be comfortable," he said, urging anyone who came to bring food and supplies for five days.

Meanwhile, some tourists were determined to face down the storm in the hotels of the city's historic French quarter. "We're choosing the better of two evils," said Bryan Steven of Minnesota, with his wife Tina. "It's either be stuck in the hotel or stuck on the road."