Federal officials had earlier predicted that the toll might skyrocket. "I think it's evident it's in the thousands," said Health and Human Services Secretary Michael Leavitt.
In the first official count in the New Orleans area, Louisiana authorities have verified 59 deaths, 10 of them at the Superdome.
Adding to the misery of this beleaguered city, some 400 to 500 police officers from New Orleans' 1,600 member force were unaccounted for, Deputy Police Chief W.J. Riley said.
Besides the lawlessness, civilian deaths and uncertainty about their families, New Orleans' police have had to deal with suicides in their ranks. Two officers took their lives, including the department spokesman, Paul Accardo, who died Saturday, according to Riley. Both shot themselves in the head, he said.
Reinforcements for police poured down the interstates toward New Orleans,long convoys of police cars, blue lights flashing, emblazoned with emblems from scattered police, sheriff, and other jurisdictions, in and out of state.
Riley said some of the missing officers lost their homes and some are looking for their families. "Some simply left because they said they could not deal with the catastrophe," he said.
Nagin said he was arranging to rotate out beleaguered emergency workers, who have been working virtually around the clock since before the storm hit.
He said police officers, firefighters and their families would get five or more days in cities with large numbers of hotel rooms, Atlanta and Las Vegas in particular. In addition to rest and relaxation, he said, they will have time to assess their personal situation.
In a related development, President Bush returned to Louisiana on Monday for another ground inspection tour of Gulf States pummeled by Hurricane Katrina, acknowledging at his first stop that "we've got work to do" so long as the suffering continues.
Upon arrival, Bush went to the Bethany World Prayer Center, a huge hall half covered with pallets and half filled with dining tables. Several people ran up to meet him as he and first lady Laura Bush wandered around the room. But just as many hung back and just looked on.
"I'm not star-struck. I need answers," said Mildred Brown, who has been there since Tuesday with her husband, mother-in-law and cousin. "I'm not interested in hand-shaking. I'm not interested in photo ops. This is going to take a lot of money."
Bush praised the volunteers and churches that have been working to take care of storm refugees. "The response of the country has been amazing," he said.
"All levels of the government are doing the best they can," said Bush, whose administration has come under withering criticism for a slow federal response to the storm. "So long as any life is in danger, we've got work to do," he said.
"Where it's not going right," he promised, "we're going to make it right."
Bush hasn't gone a day without a public event devoted to the storm and its aftermath. But none of those trips so far, nor appearances by several Cabinet members in the region, has quieted complaints that Washington's response to the disaster has been sluggish.
In suburban New Orleans, meanwhile, miles-long lines of vehicles crawled into parts of Jefferson Parish Monday as residents were allowed to return briefly to see what is left of their homes.
The traffic began moving in around 6 a.m., and officials planned to allow traffic in for 12 hours, though they encouraged residents to inspect their property, pick up personal items and leave. Most of the single-story bungalow homes in the area had water nearly to the rooflines.
Earlier in New Orleans, police shot eight people, killing five or six, after gunmen opened fire on a group of contractors traveling across a bridge on their way to make repairs, authorities said.
Air and boat crews searched flooded neighborhoods for survivors, and federal officials urged those still left in New Orleans to leave for their own safety.
Aaron Broussard, president of Jefferson Parish, just south of New Orleans, expressed his frustration with the federal government's recovery response on CBS' Early Show.
"They don't want America to know just how many people have been murdered in New Orleans because of their inefficiency."
"They're holding back the horror from the nation to try to get their act together. And then by the time they get it together, the body counts are going to far surpass Iraq, so far surpass Afghanistan."
In other developments:
Red Cross spokeswoman Tracy Gary said the relief agency was caring for 135,000 survivors across 14 states. At least 470 shelters were operating by Monday and Red Cross chapters across the country were alerted to find additional locations as victims are sent out of the Gulf Coast.
More than 5,000 Red Cross volunteers made their way to the disaster areas any way they could get there, joining thousands of volunteers from the affected areas. The agency has raised more than $400 million so far.