Looting and lawlessness are widespread in flood-stricken New Orleans as people made homeless by Hurricane Katrina grow increasingly desperate.
It is hot and humid in the stadium and toilets are overflowing
There are reports of shootings, carjackings and thefts across the city, where a full evacuation is under way.
Medical evacuations from the Superdome stadium have been disrupted after a gun shot was fired at a rescue helicopter.
President George W Bush, who will visit the disaster area on Friday, called for "zero tolerance" against law-breakers.
His Homeland Security Secretary Michael Chertoff said more national guards were being sent in the next few days - more than quadrupling the number of security personnel in the city.
Hundreds or even thousands of people are feared to have drowned in New Orleans, where the hurricane struck on Monday.
The government has declared a public health emergency along the whole of the Gulf coast. In Mississippi, 110 people are confirmed dead, but officials warn the toll is expected to rise.
Suspending the helicopter rescues at the Superdome, a spokesman for the Louisiana ambulance service told the BBC the crowd had grown unruly and he was concerned for the safety of his staff.
Overnight, a national guard was shot outside the stadium, but he was not seriously injured, a National Guard officer said.
City in exile
More than a million people were evacuated from the New Orleans and the surrounding areas before the hurricane struck, but Mayor Ray Nagin has estimated that up to 100,000 people decided to stay in the city.
During the storm, more than 9,000 people took shelter at the Superdome, but once the extent of the damage became clear the numbers swelled to 20,000.
Conditions there have sharply deteriorated and a massive evacuation is under way.
Mayor Nagin, ordering all residents to abandon the low-lying city, has warned it will be months before people can return to their homes.
Bus-loads of people are being taken 560km (350 miles) away to Houston's Astrodome stadium in Texas, where beds and blankets for up to 25,000 people have been set up. The most vulnerable are going to the Louisiana state capital, Baton Rouge.
The BBC's Alistair Leithead in New Orleans says there is a feeling of foreboding as those marooned become more desperate.
There is no electricity, and people who have lost everything are struggling to find food and clean water.
"We are out here like pure animals. We don't have help," Rev Issac Clark told the Associated Press news agency outside the city's convention centre, where dead bodies are still lying in the open.
People have faced shoot-outs and some reports say martial law has been imposed in some areas. Armed gangs have moved into some hotels.
Some have been breaking into shops, houses, hospitals and office buildings.
Thieves used a forklift truck to break into a pharmacy, AP news agency reports, while dozens of carjackings have been reported.
Louisiana state Governor Kathleen Blanco said she was "furious" at the growing crime wave.
She has asked Washington to send more people to help with the relief mission, to free National Guard troops to concentrate on looters.
In Mississippi, curfews are in place in the hard-hit towns of Biloxi and Gulfport as the authorities try to prevent the scale of looting seen in New Orleans.
President Bush, who flew over flood-stricken areas on Wednesday, compared the devastation to the 11 September 2001 attacks.
"It is so devastating that it is hard to describe it. 9/11 was a man made attack. This was a natural disaster," he said.
"New Orleans is more devastated than New York was - and just physically devastated as is the coast of Mississippi so we've got a lot of work to do and we'll get it done."