President Bush has said the US's first response to Hurricane Katrina was "not acceptable", and a huge effort is now being made to save lives.
Thousands are still stranded in New Orleans without food or water.
Mr Bush visited the region devastated by the huge storm, and told people there that the city of New Orleans would emerge from its "darkest days".
The US government has agreed to send over £5.7 billion of aid to help those stranded by the hurricane.
A National Guard convoy carrying aid reached the city on Friday.
Earlier, a series of massive explosions rocked the riverfront of New Orleans. The blasts apparently took place at a chemical plant.
The city's mayor issued a "desperate" plea for help for thousands of people still without food and water after widespread flooding.
Many people have turned to crime as they get more desperate and troops are trying to calm things down.
Soldiers brought in
Three hundred guardsmen have been called back from Iraq to bring about order.
They join 28,000 other soldiers who are attempting to keep things calm.
Up to 20,000 people are sheltering at a convention centre in New Orleans. Hundreds or even thousands of people are feared to have drowned in the city.
In nearby Mississippi, 100 people are confirmed dead, but this is expected to rise.
It's thought an area as big as the UK has been affected by the hurricane.
President Bush is set to tour the Alabama and Mississippi coast by helicopter before visiting New Orleans.