Rescue workers are continuing their efforts to get the remaining residents of New Orleans to leave their flooded city.  Meanwhile, President Bush and members of Congress have pledged to hold separate investigations into the governmental response to the tragedy.

Engineers began the slow process of pumping the filthy water from New Orleans Tuesday, even as officials urged remaining residents to leave their flooded city.

Water levels in some flooded areas were slowly receding as the breaks in the levees that were supposed to protect the city from flooding were closed. But, meeting with reporters, New Orleans Mayor Ray Nagin said mandatory evacuation remains in force because the city is not safe.

"I would like for everybody to get out because it's a health risk," said Mr. Nagin.  "There are toxins in the water.  There are gas leaks where we may have explosions.  We're fighting at least four fires right now, and we don't have running water.  It is not safe."

In an interview earlier on NBC's "Today" show, Mayor Nagin said what he has seen of the situation in New Orleans only hints at the horrors to come.

"There were bodies in the water," he added.  "I've gotten reports from firefighters that when they went to rescue people, they saw bodies in homes.  It's going to be awful and it's going to wake the nation up again."

But while most of the city's residents were rescued and evacuated, some stubbornly remain, refusing to leave their flooded homes.  Garrett Wilson, who drove his airboat from Jacksonville, Florida to New Orleans to help in rescue efforts, says people are laboring under the delusion that they can ride out the crisis, just as they thought they could ride out the storm.

"A bunch of dead bodies that have been out there for a week and the people that are in the delusion that it is going to be okay in a day or two," said Mr. Wilson.  "They can't get that through their head.  I talked to a hundred of them who said, leave me alone.  It's sad because not all of them might not die, but a lot of them are going to."

In Washington, President Bush said he was dispatching Vice President Dick Cheney to the battered Gulf Coast to assess relief efforts.

"He'll help me determine or not whether we are meeting these goals.  He'll work with [Homeland Security] Secretary [Michael] Chertoff and others to make sure that we remove any obstacles, bureaucratic obstacles that may be preventing us from achieving our goals," said Mr. Bush.  "In other words, bureaucracy is not going to stand in the way of getting the job done for the people."

Local and state officials, particularly in Louisiana, have bitterly criticized what they see as a slow response to the plight of people caught in the disaster. 

Appearing on the CBS-TV "Early Show," Aaron Broussard, president of Jefferson Parish just outside New Orleans, remains angry.

"Bureaucracy has murdered people in the greater New Orleans area," he said.  "And bureaucracy needs to stand trial before Congress today.  So I'm asking Congress, please investigate this now. Take whatever idiot they have at the top of whatever agency and give me a better idiot. Give me a caring idiot. Give me a sensitive idiot. Just don't give me the same idiot."

Congress has pledged an investigation into the federal response.  President Bush likewise promised Tuesday to lead his own investigation to determine, as he put it, "what went right and what went wrong" in the response to Hurricane Katrina.