A British tourist stranded for five days with his wife and seven-year-old son in a New Orleans hotel has called the US relief operation a "shambles".
Staff and guests chased one group of looters from the building
Ged Scott, 36, of Liverpool, told BBC News that hotel staff and guests had received no help from the authorities.
Police officers had taken "souvenir" photographs of stranded people begging for help, he added.
He told BBC News he had helped to mount security patrols in the hotel while shots rang out nearby.
"We saw people making their way down the rivers that were streets, dragging their last belongings with them," Mr Scott, a bus driver, said.
He told BBC News he had been on his annual holiday at New Orleans' Ramada Hotel with his wife Sandra, 37, and their seven-year-old son, Ronan.
Without their driving licences they were unable to hire a car and flee the city ahead of the storm and decided to remain in their hotel after being warned the Superdome would be too dangerous.
The handling of the relief operation had been "horrendous", Mr Scott added.
"I could not describe how bad the authorities were - taking photographs of us as we are standing on the roof waving for help, for their own personal photo albums, little snapshot photographs."
He said at one point a group of girls was standing on the roof of the hotel lobby and called to passing rescuers for help.
"They [the authorities] said to them 'well show us what you've got' - doing signs for them to lift their t-shirts up. The girls said no, and they said 'well fine', and motored off down the road in their motorboat.
"That's the sort of help we had from the authorities," he said.
Mr Scott added: "The only information we got from anybody in authority was if a policeman came past and we shouted to them out of the windows.
"The only information we ever got off them was negative, 'Do not go here. Do not go there'.
"There was no, 'Are you OK? Are you safe? Have you got water?'.
"Most of the time they would ignore us."
New Orleans remains under water
At night, the police presence disappeared altogether, leaving the stranded guests and staff to defend themselves.
"You would hear shots ringing out during the night and that was one of the most worrying things, because we had no security," Mr Scott said.
"We patrolled the halls and checked the doors throughout the night in the hotel - but if someone had wanted to come in, there was not much we could have done about it."
They had a torch - but, Mr Scott said, "you knew if you went down in the dark the torch would only make you a better target".
Nevertheless, the staff and guests had managed to chase one group of looters from the building, he added.
He then had had to wade waist-deep through the filthy water to barricade the hotel's doors.
"It was like wading through an open sewer.
"It reeked to high heaven and made you want to vomit.
"Outside I could see bodies floating in the water."
Mr Scott told BBC News he had ripped wires attached to speakers from the walls of the flooded hotel bar and tied tables and chairs together as makeshift barricades.
He had then run back upstairs for "the best wash I have ever had" - using water from the toilet cistern, he added.
Looters also tried to sell the stranded guests mobile phones, radios and clothes.
When they were finally rescued it had been by Louisiana game wardens, who had entered the hotel with rifles and fixed bayonets, Mr Scott said.
Now back in the UK, he said he was worried about the effect the experience had had on his son.
"He was fantastic - but he has been exposed to things no seven-year-old should ever see and it is bound to come out in the future."
In an earlier response to calls by former US president Bill Clinton for an inquiry into how the federal government responded to Hurricane Katrina, Linda Saccia of the Federal Emergency Management Agency said it was too early to criticise the relief effort.
"There are 30,000 responders, rescuers, recovery people, law enforcement that are working night and day and I wouldn't say anything or even quite frankly think anything that would be negative towards their hard work.
"The studies that will be done afterwards will prove and show what did and didn't go well," she said.