By Alastair Leithead
BBC News, New Orleans
The people of New Orleans awoke to see what Hurricane Katrina had done to their city.
They found street after street after street under water. The city is now cut off to all but boats and helicopters, and hundreds of people have been stranded.
New Orleans missed the storm's eye, but the cost is still huge
Many have already been airlifted to safety. Others compete for the attention of the emergency services.
And the flooding goes on for mile after mile.
Many people left when they could. Others were caught out by the intensity of the storm, as 140mph (225kp/h) winds blew out windows and left a trail of debris.
The city's citizens are now relying on a massive rescue effort.
There is no power, even when people can get to safety.
Supplies are running low in some areas, while the water is contaminated and must be boiled before it can be drunk.
Downtown 'cut off'
On Canal Street, in the middle of downtown New Orleans and on the fringes of the historic French Quarter, the water levels are still rising steadily.
Downtown was the one place people thought would escape flooding, because it is slightly higher than the rest of the city.
Boats are being used to reach people in areas cut off by floods
But as the water pouring in from the lakes around the city keeps pushing the flood level further and further up, the area has become completely cut off.
No-one can get out and no-one can get in.
Boats have been seen sailing down, trying to work out how to get people away, as police attempt to evacuate the area.
Elsewhere in the city, many citizens are still hunkered down in the Superdome sports stadium, where they sought refuge ahead of the storm. The winds tore at the roof but they were safe.
Others cannot even venture from hotels to see if their homes are still there.
Some opportunists are already taking advantage of the situation to loot stores and homes.
The police are trying to do what they can in difficult circumstances. Martial law could be the answer.
Across the border in the state of Mississippi, the town of Biloxi was hit. In one block of flats, 30 people are reported to have died.
Some 450,000 people in Mississippi are without power, while in south-east Louisiana the figure stands at 370,000.
The cost of the damage inflicted as winds tossed away man-made structures like toys is expected to run into billions of dollars.
As Katrina moves inland the storm's force is weakening.
But the damage has already been done - and for the people of this flooded city, the suffering is just beginning.