New Orleans Mayor Ray Nagin says hundreds, or "most likely thousands" of people in the southern U.S. city have been killed by Hurricane Katrina.
During a televised news conference Wednesday, Mr. Nagin said there are a significant number of bodies in the water that now covers most of the city, and that other people died in attics.
He said it will be at least two or three months before the city regains electricity.
U.S. officials have declared a public health emergency for areas along the U.S. Gulf of Mexico in the aftermath of the devastating storm.
Health and Human Services Secretary Michael Leavitt made the declaration Wednesday as authorities struggled to rescue survivors and restore order in the region.
Meanwhile, the U.S. military says another 10-thousand National Guard troops will be deployed to Louisiana and Mississippi to help maintain law and order. Looting has taken place in many areas as people raid businesses, stealing food supplies and other goods.
In the neighboring state of Mississippi, Governor Haley Barbour says Katrina wiped out 90 percent of the buildings near the coast in the cities of Gulfport and Biloxi.
U.S. Homeland Security Secretary Michael Chertoff says U.S. officials will work tirelessly to aid the victims. The government says it is sending medical emergency teams and truckloads of basic supplies such as ice and electric generators.