One of the most powerful hurricanes to hit the United States has come ashore, threatening massive flooding and wind damage in Louisiana and other states bordering the Gulf of Mexico. The storm weakened slightly before hitting land for a second time, but is still considered a very dangerous storm.
Hurricane Katrina made landfall at Grand Isle, on the Louisiana coast, just before sunrise. At the time, its top winds were estimated at about almost 240 kilometers per hour.
There is a mandatory evacuation order in New Orleans, a city of nearly half a million people. Forecasters said the hurricane's six meter storm surge is more than capable of swamping the city. Most of New Orleans lies below sea level, protected by earthen embankments and pumps that may not withstand the waves pushed by the storm's winds.
Some 10,000 people who were unable to leave the city took shelter in the Louisiana Superdome football stadium. But officials are expressing concern about the building, as strong winds have torn small holes in the giant roof. The stadium also lost electricity at about five am local time. Back-up generators restored lighting, but not air conditioning.
From the state's emergency operations center in Baton Rouge, Louisiana Governor Kathleen Blanco urged residents to remain calm and be patient.
"Remember that some streets and roads will be flooded and may not be passable," she said. "Trees will be down. Power will be out. So, in some cases, probably in many cases, people will not be able to return immediately to their homes."
The hurricane crossed southern Florida as a much weaker storm last week and was blamed for nine deaths.
Katrina is expected to weaken after moving inland, but forecasters said it would still be a hurricane for another day as it moves through the southeastern United States.