Tropical Storm Isaac has been upgraded to hurricane level as it smashed into the Louisiana coast.
Lashing the coastal region with winds up to a speed of 80mph (130km/h), Hurricane Isaac was heading toward New Orleans, the city which was devastated seven years ago by Hurricane Katrina. Isaac was likely to weaken during its course, the National Hurricane Centre forecast.
Thousands of people were without power supply in Louisiana.
Although the latest hurricane is not as devastating as Katrina, it has the potential to cause huge floods and high winds. This will also be the litmus test for the multi-billion dollar flood defence mechanisms which are put in place in New Orleans.
After the disaster caused by Katrina, miles of levees and flood walls have been erected at a cost of $14.5 billion (£9.1 billion).
Authorities in the states say they are much prepared for the situation after the 2005 catastrophe.
US President Barack Obama has asked the people who are in the path of Hurricane Isaac to take precautionary measures.
"I want to encourage all residents of the Gulf Coast to listen to your local officials and follow their directions - including if they tell you to evacuate.
Now is not the time to tempt fate. Now is not the time to dismiss official warnings. You need to take this seriously," said Obama.
While thousands of people have left the area, many others stayed behind closed doors as there was no mandatory evacuation in place.
Assuring the people that New Orleans would be secure, Mayor Mitch Landrieu said, "We will not have a Katrina-like event. Do not let this storm lull you into complacency. People may be getting bored. It's better to be bored than to get hurt."
Stating that the city's airport was closed, Landrieu said, "We're in the heart of this fight. We are in the hunker-down phase."
US National Guard troops are also deployed in the city to prevent any looting.
Nearby states including Mississippi, Alabama are also kept in high alert for rainfall.