Five days later, he told Oprah Winfrey that babies were being raped. On the same show, mayor Ray Nagin warned: "They have people standing out there, have been in that frickin' Superdome for five days watching dead bodies, watching hooligans killing people, raping people."
The ugliest reports - children with slit throats, women dragged off and raped, corpses piling up in the basement - soon became a searing image of post-Katrina New Orleans.
The stories were told by residents trapped inside the Superdome and convention centre and were repeated by public officials.
Many news organisations, including The Associated Press, carried the witness accounts and official pronouncements, and in some cases later repeated the claims as fact, without attribution.
No official reports
But now, a month after the chaos subsided, police are re-examining the reports and finding that many of them have little or no basis in fact.
Mayor Ray Nagin's aide says he
relied on others for information
They have no official reports of rape and no witnesses to sexual assault.
The state department of health and hospitals counted 10 dead at the Superdome and four at the convention centre. Only two of those are thought to have been murdered.
One of those victims, found at the Superdome, appears to have been killed elsewhere before being brought to the stadium, said Bob Johannessen, the agency spokesman.
"It was a chaotic time for the city. Now that we've had a chance to reflect back on that situation, we're able to say right now that things were not the way they appeared," said police Captain Marlon Defillo.
Sally Forman, a spokeswoman for Nagin, said the mayor was relying on others for his information about conditions at the evacuation sites.
"He was listening to officials, trusting that information they were providing was accurate," she said.
Conditions at both sites were chaotic.
Water was rising around the Superdome, home to 20,000 evacuees.
Toilets were backing up, garbage was rotting, fights were breaking out. Food was in short supply at the convention centre, where people took shelter from the rising waters.
The temperature was climbing. The elderly and very young were desperate for food, water and medicine.
A sign warns media at the
entrance of a Louisiana morgue
A week after the floodwaters poured into the city, an Arkansas national guardsman told The Times-Picayune of New Orleans that soldiers had discovered 30 to 40 bodies inside a freezer in the convention centre's food area.
Guardsman Mikel Brooks told the newspaper that some of the dead appeared to have met violent ends, including "a 7-year-old with her throat cut".
When the convention centre was swept, however, no such pile of bodies was found.
Lieutenant-Colonel Jacques Thibodeaux of the Louisiana National Guard said reports of violence at the Superdome and the convention centre were overblown.
He was head of security at the Superdome and led the 1000 military police and infantrymen who went in to secure the centre on 2 September.
"The incidents were highly exaggerated", the result of fear and hopelessness, he said. "For the amount of the people in the situation, it was a very stable environment."
Thibodeaux said his guard unit received no reports of rape.
"Rumours become improvised news. You become your own anchorman"
Bill Ellis, folklorist at Pennsylvania State University
Bill Waldron, a homicide detective from Florida in New Orleans for a murder trial, was stuck in the convention centre until 1 September.
He said he saw a couple of fights between young men, but "no murders, no rapes".
He said that he did see people dying, but that those deaths were most likely a result of the heat and lack of water.
"People were wanting just some type of authority to come in and say, 'Hey, this is what's going to happen'," Waldron said. "People were scared."
New Orleans District Attorney Eddie Jordan said officials at the morgue in St Gabriel had identified four apparent homicide victims from the city.
All were shot and all were adults. Police arrested one person on suspicion of attempted sexual assault but received no official reports of rape.
Too soon to say
Judy Benitez, executive director of the Louisiana Foundation Against Sexual Assault, cautioned that it might be too soon to say whether there really were rapes at the evacuation sites.
Because the evacuees and any perpetrators have been scattered across the country by Katrina, and now Hurricane Rita, victims may come forward later, she said.
"It is extremely difficult to get good statistics about rape under normal circumstances, and these are certainly not normal circumstances," she said.
Contrary to reports, no children
with slit throats were found
Bill Ellis, a folklorist at Pennsylvania State University, said rumours in an environment like that at the evacuation centres are to be expected, given the frightening circumstances and paucity of authoritative information.
"Rumours become improvised news. You become your own anchorman," he said.
The chaos also seemed to affect some reporters and editors, said Kelly McBride, who teaches ethics to journalists at the Poynter Institute, a journalism research and education centre in St Petersburg, Florida.
"You get so hung up as a reporter on what the big picture is that you use generalisations that become untrue," McBride said.