President George W. Bush assembled his Cabinet on Wednesday, and then addressed the nation, warning that the recovery from Hurricane Katrina will take years.

Meanwhile, 10,000 more National Guard troops from across the country are heading into the Gulf Coast region.

That brings the number of troops dedicated to the recovery effort to more than 28,000.

One commander said about one-third of the troops will be assigned to help stop looting, enforce curfews and assist local police.

There are also thousands of Navy personnel and hundreds of workers with the Army Corps of Engineers responding to the disaster.

The commander of the National Guard, Lt. Gen. Steven Blum, said the disaster might require the largest ever national response.

Bush called the destruction wreaked by Hurricane Katrina "one of the worst natural disasters in our nation's history."

It is also one of the most widespread disasters. Katrina has caused huge increases in gas prices around the country.

Secretary of Homeland Security Michael Chertoff was placed in charge of a federal task force to coordinate the nation's response, and Federal Emergency Management Agency Director Mike Brown will manage work in the field.

Bush stressed that federal officials will work with local officials to make sure they are "helping, not hindering."

Earlier, Bush viewed the hurricane damage from above.

His flight Wednesday from his Texas ranch to Washington detoured over the storm's path. Air Force One descended to an altitude of about 5,000 feet so that Bush could view some of the most damaged areas.

The president might visit the storm area later in the week.

Despite a worsening situation and rising death toll, Bush sees hope down the road.

He said the Department of Transportation is loading up 400 trucks with food, water and cots, and that a Navy hospital ship is en route.

Bush called on Americans to contribute to the Red Cross or call 1-800-HELP-NOW.

"New communities will flourish ... The great city of New Orleans will be back on its feet," he said.

Mayor: Police Will Stop Looters 'Right Now'

New Orleans Mayor Ray Nagin has pulled 1,500 police officers off their search-and-rescue mission and has reassigned them to go after looters.

Nagin told The Associated Press that looters are starting to get closer to heavily populated areas, including hotels and hospitals. He said police will "stop it right now."

Even a nursing home was targeted by looters, who took a bus and threatened the driver and residents. The home plans to relocate residents and its director said she's considering arming workers.

The top Homeland Security official in New Orleans said bands of gunmen are roaming through the city.

Terry Ebbert said looters have been breaking into stores all over town to steal guns. The Times-Picayune newspaper reported that the gun section at a new Wal-Mart was cleaned out. And the thieves are apparently using their new guns, with shots heard through the night.

Guns aren't the only things drawing the thieves. People commandeered a forklift in high ground to lift storm shutters and break the glass of a Rite-Aid pharmacy. A crowd stormed the store, carrying away ice, water and food.

A spokeswoman for Louisiana's governor said workers at Children's Hospital huddled with sick kids and waited for help to arrive as looters tried to break in, but help never came.

A city councilwoman said, "The French Quarter has been attacked."

What police presence there is in New Orleans and Biloxi, Miss., isn't slowing down looters.

A police spokesman in New Orleans said a police officer was shot in the head by a looter, but he's expected to recover.

Dozens of looters on historic Canal Street ripped open steel gates to stores. Some filled plastic garbage cans to carry or float stolen goods.

In Biloxi, looters picked through slot machines of damaged casinos to see if they still had coins inside.

One motel owner said people are just "filling up garbage bags and walking off like they're Santa Claus."

Thousands May Be Dead

Nagin said there might be thousands of people dead in New Orleans in the wake of Katrina.

He said at least hundreds of people have been killed in New Orleans by the storm, but that the number is likely higher. When asked for a figure, he told reporters, "Minimum hundreds, most likely thousands."

Nagin said authorities know there are a "significant number" of dead bodies in the water that now covers most of the city, and that others died in attics.

The mayor spoke Wednesday at an impromptu news conference at the Hyatt Hotel. He said it will be at least two or three months before New Orleans has electricity. During that time, he said, there will be no commerce in the city, and restaurants won't be able to open.

Nagin said earlier that rescue boats are bypassing the dead in search of survivors, many of whom have been stranded on the roofs of their homes since Monday afternoon.

Maj. Gen. Don Riley said it could take close to a month to pump floodwater out of the city. The Coast Guard said it has used boats to rescue 1,200 stranded people.

One survivor after another told of friends and loved ones who floated off or disappeared as the floodwaters rose around them.

Louisiana Gov. Kathleen Blanco said the devastation "is greater than our worst fears." She described it as "totally overwhelming."

Hospitals Doing Their Best

National Guard troops evacuated 300 patients from Charity Hospital in New Orleans, which is surrounded by water. There's no working plumbing or electricity at Charity, but patients keep coming.

Nurses held flashlights and ventilated patients by hand. Doctors wearing green scrubs used canoes to ferry supplies between the city's four downtown hospitals.

As a boat pulled up carrying a man doubled over in pain, nursing supervisor Ray Campo said it's like running into a burning building looking for shelter.

Ambulance helicopters took babies to hospitals all around Louisiana and airlifted doctors into New Orleans.

The governor said the storm severed a major water main, leaving the city without drinkable water.

Refugees To Move To Astrodome

The evacuees from Hurricane Katrina who have been housed at the Louisiana Superdome will be headed to Houston, where a shelter is being set up for them at the Astrodome.

FEMA is providing nearly 500 buses for a convoy that will begin Wednesday, traveling the 350 miles to Houston. The evacuees began arriving in Houston Wednesday night.

A spokeswoman for Texas Gov. Rick Perry said the Astrodome's schedule has been cleared through December to serve as a shelter for evacuees.

An emergency management official in Houston told The Associated Press that plans are in the works to provide a "full shelter operation for 25,000 people."

Most of them will come from the Superdome. Conditions there have deteriorated rapidly since the storm came through. It knocked out the air conditioning and tore holes in the roof, and toilets there are broken.

Rising floodwaters in New Orleans prompted the state's governor to order the stadium and the city abandoned. She said that all evacuees in New Orleans would have to be moved out of the city.

Harris County Judge Robert Eckles said the Astrodome is using plans that would be implemented in the event of a disaster in Houston, reported KPRC-TV in Houston.

"The disaster in Louisiana has been of such epic proportions that they are overwhelmed. They have people that have no water, no food and no means to get them there," Eckles said.

The American Red Cross said it would operate the Astrodome relief center for several weeks but not longer.

"Physically, we can do it for several months. As a practical matter, living in a stadium with 20,000 other people in a common area is not a healthy place to be," Eckles said.

"We are bringing people who are refugees from Louisiana specifically to the dome. If we start having everyone who is camped out on the side of the road or at hotels show up at the dome, we do not have room for them. We will turn them away," Eckles said further.

The Astrodome was a first-of-its-kind indoor sports arena when it opened 40 years ago, but it hasn't been used for professional sports events in years.

Social Security To Cut Emergency Checks For Evacuees

Some of the retirees who've fled their homes because of Hurricane Katrina may be wondering how they'll get their monthly Social Security check.

The Social Security Administration said it's working on a system to make sure that displaced elderly or disabled recipients are able to get their funds.

A spokeswoman said the agency will still send payments through direct deposit or by mail. But, she said if someone doesn't get their money, they can request an emergency payment from any Social Security office.

Because many people don't have access to a bank or their identification papers, Social Security is working on having checks delivered to temporary disaster centers.

Families receiving state aid from Louisiana, Mississippi and Alabama can access their money from certain ATM machines.

Plugging Levees A 'Nightmare'

Louisiana's governor said trying to plug the leaking levees in New Orleans is an "engineering nightmare."

Blanco said workers will try dumping concrete barriers into the gaps to halt the flow of water from Lake Pontchartrain that's filling up the city like a bathtub. Sandbags alone aren't working.

She said the levee repairs and rescuing people are the top priorities.

She's also addressed the looting problem, saying authorities intend to restore law and order.

Blanco asked for the nation's prayers and said the disaster "will give us an opportunity for rebirth."

An estimated 80 percent of the below-sea-level city is under water. Water is up to 20 feet deep in some places.

The entire city could soon be flooded if repair efforts fail, the mayor said.

FEMA Wants Homeland Security Help

Federal emergency officials are looking for 2,000 Homeland Security Department workers to volunteer for hurricane relief efforts.

The FEMA director told Homeland Security Secretary Chertoff that 1,000 people are needed within 48 hours and 2,000 within a week.

Volunteers will get training in Maryland, Atlanta or Orlando, Fla. FEMA said it's looking for special skills like being bilingual or having a commercial driver's license.

Volunteers are being told they must be able to work long hours outdoors. They've also been advised to bring sunscreen, walking shoes, mosquito repellent and other gear.

The government has also asked Carnival Cruise Lines if it can help.

More Than 100 Reported Dead In Mississippi

Hurricane Katrina has killed more than 100 people in Mississippi and officials are "very, very worried" the number will go much higher.

At least 100 died in Harrison County, home to Biloxi and Gulfport.

A county coroner said Wednesday afternoon that search-and-rescue teams have only been able to get into about half of the areas virtually destroyed.

Gary Hargrove said it "may be several days or even weeks" before teams can get into some areas of coastal Mississippi. He also noted that buildings that survived Hurricane Camille in 1969 were "pancaked" by Katrina.

Hargrove, who experienced Camille, said, "This storm was worse than Camille."

Officials have confirmed 10 other deaths in two small communities in Jackson County.

After touring the destruction by air, Mississippi Gov. Haley Barbour said it is not a case of homes being severely damaged, "they're simply not there. ... I can only imagine that this is what Hiroshima looked like 60 years ago."

Barbour said his state has turned a corner, but there are "lots of corners left to go" in recovering from Hurricane Katrina.

The governor said the first 24 hours after the massive storm were the worst, because emergency workers and survivors couldn't move. He said the state's roads were all blocked with trees, debris and downed power lines.

Barbour said rescuers are extending their reach now.

The governor is also thanking Ohio, Florida and other states for sending help. Barbour said he's stunned by the damage. He said 25 to 30 miles of the Gulf Coast are "absolutely obliterated."

Tuesday night, more than 900,000 customers in the state lacked power.

Pentagon Coordinating Massive Response

Every branch of the U.S. military is involved in the rescue-and-relief mission following the storm.

The U.S. Northern Command is coordinating search and rescue, medical help and supplies. The work will support FEMA and the states of Louisiana, Mississippi and Alabama.

The Army and Air Force are providing search-and-rescue helicopters. The Army Corps of Engineers is organizing one of its largest response efforts in recent memory.

The Navy said four of its ships loaded with provisions such as food, water, soap and medical supplies are preparing to leave Virginia. They're expected in the Gulf by the weekend.

The hospital ship USNS Comfort is leaving Baltimore for the Gulf, and eight swift water rescue teams from California are on the way to Louisiana.