A huge rescue operation is under way along the US Gulf Coast after a hurricane killed up to 80 people in a single county and swamped New Orleans.
Harrison County in Mississippi bore the brunt of Hurricane Katrina as it slammed into local towns Biloxi and Gulfport before heading inland.
Mississippi media earlier recorded a death toll of 54 for the state.
Thirty people are said to have died in one block of flats in Biloxi which was hit by a 9m (30ft) water surge.
The town's actual death toll may be "in the hundreds", municipal spokesman Vincent Creel told Reuters news agency.
Beyond Mississippi, an unknown number of bodies were seen floating in the flood waters of New Orleans, Louisiana.
With two dams breached, water is still flooding into the city from Lake Pontchartrain - in some areas it has reached rooftop level.
Food and clean water supplies are running low. Martial law has been declared in some areas to tackle looting.
Forecasters have warned of heavy rain as the storm heads north towards Tennessee and Ohio. Tornado warnings are in force in some areas.
Mississippi Governor Haley Barbour told reporters that Harrison County's death toll could reach 80.
"We know that there is a lot of the coast that we have not been able to get to," he said.
Large parts of Biloxi, where roads are impassable and telephone lines down, may have been destroyed in what Mayor AJ Holloway described as "our tsunami".
"The flooding is just everywhere... New Orleans, all through Mississippi and Alabama," said Michael Brown, director of the Federal Emergency Management Agency.
"All those low-lying areas are just devastated."
Senior Chief Petty Officer Steve Carleton, from the US Coastguard, told BBC Radio Five Live, that guards were rescuing people from rooftops, but some were "trapped in some places and cannot get through to us".
Mayor Ray Nagin of New Orleans said a huge rescue effort was under way in his city, which was 80% under flood water though the historic French Quarter escaped major damage.
"We have just about everyone you can think of out there trying to rescue individuals from their roofs," he said.
The mayor added that bodies had been spotted floating in the water but no death toll was being issued early on Tuesday.
The American Red Cross has mobilised thousands of volunteers for its biggest-ever natural disaster effort and federal emergency teams are being dispatched to affected areas.
Damage estimates of more than $25 billion suggest it could be the US insurance industry's most expensive natural disaster ever.
The price of crude oil on the international market hit a new record at $70.85 a barrel due to the vulnerability of oil and gas fields in the Gulf of Mexico.
President George W Bush has called on Americans to donate to the Red Cross or other organisations to help while his priority was "saving lives".
The president was interrupting his holiday to return to the Washington two days earlier than planned, the White House said.