THE tens of thousands of us trapped in New Orleans are witnessing scenes that we never thought we would see in the 21st century in a major western city.

Hurricane Katrina has washed away escape routes and swallowed streets whole. There is no electricity or running water. Telephone lines are down. The mobile phone system has crashed.

The levees surrounding New Orleans have been breached and torrents of water are pouring into the bowl in which the city sits. The pumps have been overwhelmed. Four-fifths of the city is under water, including both airports, and the tide is lapping around the historic French Quarter.

The mayor is talking of bodies floating through the streets, the authorities have imposed martial law, and looters are ransacking shops.

Hospitals are considering evacuation. An estimated 20,000 people have taken refuge in the Superdome. The Times-Picayune, the city’s newspaper, has abandoned its offices. Rescuers are searching the city in boats and helicopters, plucking residents from rooftops. Authorities even reported that a 3ft shark had been spotted cruising the streets.

Outside my downtown hotel, packed with 500 refugees, there is a knee-high soup of brown water swirling with debris — lethal shards of glass, road signs, sheets of metal, tree branches and lampposts.

People are wading out of the flooded lobby, trying to reach their cars to take the only route that remains out of the city after the twin span causeway that leads across Lake Pontchartrain to the north was swept away.

Many are carrying pillows and blankets on their heads and possessions on their backs. One man mustered friends and family to carry his 100-year-old grandmother down five flights of stairs and on to a truck.

Some of the refugees have only the clothes on their backs. Some have no food, and many are relying on the hotel’s dwindling handouts of bottled water for hydration. Many have children. Some even brought their dogs and a number are infirm, disabled or in wheelchairs.

There is misery, fear, desperation and — for those who did not heed the evacuation warnings — regret. “I wish I had evacuated when I could,” said Anthony Peterson, 27. “I wish I’d listened. Now we’re trapped like rats. I went to bed on Monday night with the streets dry and I woke up this morning to find I’m in Waterworld. The toilet isn’t working, my mobile phone doesn’t work and we only have a few cans of food that we are trying to stretch between four of us.”

Mr Peterson’s home, close to Lake Pontchartrain, is probably under 15 feet of water. “We might have to start our lives all over again when we get out of this,” he lamented. “My only consolation is that I work as a roofer, so I’ll have plenty of customers.”

From my fifth-floor window I watch police SWAT teams wading down the street from their makeshift HQ in the building opposite, with their trousers rolled up and their firearms held above their heads to keep them dry.

My rental car, which I had driven 120 miles from Alabama on Sunday afternoon, is doomed. Knowing it to be the only source of power for recharging my satellite phone, I charged downstairs and attempted to move it. Sitting in the driver’s seat with water up to my knees, I managed to start it, and coaxed the vehicle 50 yards towards drier ground, pushing a wave ahead of me. But the engine gave out and the car simply started floating.

People are sitting in corridors and in their rooms huddled around radios. “The devastation is worse than our worst fears,” we hear Kathleen Blanco, Louisiana’s Governor, telling us in a breaking voice. “Pray for patience, pray for courage.”

Aaron Broussard, the Jefferson parish president, tells us the situation is “critical”. In his parish, to the east, 200 people were rescued overnight from rooftops by Coastguard and police helicopters that clattered over the city all night.

We are being told that the flood waters are coming from the breached canal levees to our north. “We always were afraid the bowl that is New Orleans would fill quickly,” says Walter Maestri, emergency management coordinator for Jefferson parish. “Now with the water rising today it appears to be filling slowly.”

The French Quarter, which usually throbs with the sounds of jazz and blues, is mainly dry, at least for the moment. Among those wandering the streets, unable to leave because there is no transport and the airports are under water, were a handful of British tourists including Cheri Smith, 23, of Glasgow, who arrived on Saturday for a few days’ holiday after completing a ten-week Camp America summer project in New York state. “At least we are safe and dry here, but it’s not going to be much fun,” she said. “This was meant to be my vacation before going home. I wanted to do all the famous sightseeing things, like wandering around the French Quarter and taking in the scene, and doing one of those swamp tours that they do. It looks like I could have got that right here.”

Other stranded tourists took pictures of looters ransacking stores. “It’s downtown Baghdad. It’s insane,” exclaimed Denise Bollinger from Philadelphia.

But the wife of a man walking down Canal Street with a pallet of food on his head denied they were stealing. “It’s about survival right now,” she said. “We’ve got to feed our children.”

Some people have taken to sun loungers beside the small rooftop pool in my hotel. The water is black with filth from the storm and unfit for anything other than flushing toilets. They are not sunbathing, even though the sun is shining. They are contemplating how long they might be here. The hotel’s back-up generator, which had enough diesel for 30 hours, is now running low and the manager has announced that he is switching off the emergency lighting to save the last of the fuel for nightfall so we at least have lights in the corridors.

The lifts do not work. People are puffing up and down the emergency stairwells, and some are smoking despite being told not to. The result is that the fire alarm has now been shrieking for three hours solid. Civic authorities have given warning that if fires break out anywhere in the area, there is no water pressure to pump the hoses and that the public will be on their own.

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