Relief and cleanup efforts in the Gulf Region will take months, but already federal emergency response teams have fanned out across Louisiana, Mississippi and Alabama to help with the aftermath of Hurricane Katrina (search), President Bush said Wednesday.

Calling it one of the "worst natural disasters in our nation's history," the president spoke after meeting with the White House disaster relief task force — Cabinet secretaries and other federal officials working to help provide relief to victims of Katrina.

The president enumerated a list of actions already taken by the federal government. He added that the amount of private help that is likely to come from concerned Americans should serve as solace to people who seemingly have nothing left after the enormous storm.

"The folks on the Gulf Coast are going to need the help of this country for a long time," the president said at a Rose Garden press announcement.

"This is going to be a difficult road. The challenges that we face on the ground are unprecedented," he said.

"But there's no doubt in my mind that we're going to succeed. Right now, the days seem awfully dark for those affected, I understand that, but I am confident that with time, you'll get your lives back in order, new communities will flourish, the great city of New Orleans will be back on its feet and America will be a stronger place for it. The country stands with you. We'll do all in our power to help you."

Cutting short his vacation to return to the White House, Air Force One flew over the damaged areas of New Orleans as well as Slidell, La., and Gulfport, Pascagoula and Biloxi, Miss. During the 35-minute tour, Bush clearly saw from his vantage point the damage to the football stadium in New Orleans as well as the flooded neighborhoods, wiped out bridges and slabs of foundations where houses used to stand.

"It's devastating. It's got to be doubly devastating on the ground," Bush told aides during the flight. "It's totally wiped out."

In the Rose Garden, Bush underscored the impact the panorama had on his resolve.

"There is a lot of work we're going to have to do. In my fly-over I saw a lot of destruction on major infrastructure.

"I have directed the folks in my Cabinet to work with local folks, local officials to develop a comprehensive strategy to rebuild the communities affected. And there's going to be a lot of rebuilding done. I can't tell you how devastating the sights were," he said.

Earlier in the day, Health and Human Services Secretary Michael Leavitt declared the situation in the Gulf Coast region a "public health emergency" while Homeland Security Secretary Michael Chertoff described the hurricane and its aftermath an "Incident of National Significance," triggering a recently developed national emergency plan for the first time. The plan allows DHS to run coordination for federal agencies working alongside state and local agencies.

In an early afternoon news conference, Chertoff said the federal agencies do not supersede state efforts but work in coordination with the states. He added that it's too early to estimate the number of dead or the ancillary costs that will mount after the initial clean-up is completed.

"I don't think we have fully assessed all the collateral consequences we're going to have to deal with," he told reporters, adding that total costs won't be added up for a while because environmental, plant and animal costs and other damages haven't yet been evaluated.

"We're going to be obviously trying as quickly as possible to assess the total damage and develop a plan for doing what we need to do to repair and rebuild, but we're not going to have a definitive answer for a while," Chertoff said.

At the same event, Leavitt said his agency is concerned about potential disease outbreaks and was sending medical experts from the Centers for Disease Control and Prevention. Leavitt said primary concerns for HHS were sanitation, food safety, mosquito abatement, water-borne illnesses and carbon monoxide poisoning.

Leavitt added that HHS was establishing medical shelters, primarily with the help of military installations.

"We are also erecting a network of up to 40 medical shelters. They will have the capacity, collectively, of 10,000 beds, and will be staffed by some 4,000 qualified medical personnel," he said.

In addition to the number of beds being made available, the federal government was in talks with the International Council of Cruise Lines about using ships as housing for storm victims.

Spokeswoman Christine Fischer said it's a possibility, but may be more difficult than at first thought.

"This is something that the cruise industry is exploring," she said. "We're trying to figure out if you're even able to get a ship up the river."

Earlier in the day, Bush held a video conference call from his home in Crawford, Texas, to discuss with senior staff and Cabinet secretaries ongoing relief efforts. Bush stressed that the first priority should be saving and sustaining lives and the second should be on a long-term plan for dealing with displaced residents, said White House spokesman Scott McClellan.

In Louisiana, Lt. Kevin Cowan, a spokesman for the state's Office of Emergency Preparedness (search), said that officials are more concerned with getting people out of New Orleans than counting the number of dead.

"There are casualties in New Orleans. I don't have the numbers at this time. Numbers are not a priority at this time because we are focusing our efforts on saving the lives that are still there. There are people trapped in their attics and the water is still rising," Cowan said.

Included in the president's call were Vice President Dick Cheney, White House aides Karl Rove, Andy Card and Dan Bartlett, Department of Homeland Security Secretary Michael Chertoff, White House Homeland Security Adviser Fran Townsend and Federal Emergency Management Agency (search) chief Mike Brown, among others.

Brown, who is running the federal response on the ground in the devastated region, updated the others on the call about the status of operations in the area, particularly on the evacuation procedures for the New Orleans Superdome. As many as 25,000 people were going to be bused from the Superdome to the Houston Astrodome in Texas as water around the New Orleans stadium is several feet high, the air conditioning and many of the toilets in the building are broken and tempers of people stuck in the building are starting to flare.

Brown also discussed the flooding and ways to fix the levees, including working with the U.S. Army Corps of Engineers. The group discussed security in the area and Brown told the group "he was getting good cooperation with state and local authorities," McClellan said.

The president is likely to tour the region later in the week, probably Friday or Saturday, though White House aides are still figuring out the timing. McClellan said the president has urged national unity in this time of crisis.

"This is a time when all Americans really need to come together and do all that we can to support those ... in the Gulf States region that have been impacted by this natural disaster," McClellan said. "This could well be the worst natural disaster in our nation's history."

McClellan said a supplemental appropriation is likely to be requested from Congress at some point to pay for disaster relief and recovery.

Senate Minority Leader Harry Reid of Nevada said he spoke with Majority Leader Bill Frist of Tennessee about setting aside time in the Senate schedule to take up relief work immediately when Congress returns on Tuesday.

"I hope the president and his administration will act swiftly to provide the Congress with damage assessments so that we can provide immediate relief to the people of the Gulf Coast. We must not waste any time in giving these families the resources they need," Reid said in a statement. "There can be no more important challenge facing our country in the days ahead than getting relief to victims of Hurricane Katrina."

International Concern

While condolences started trickling in from around the globe two full days after the widespread devastation in the southern United States left at least 100 dead in Mississippi alone, Germany and Great Britain on Wednesday were the first to offer their assistance if the United States requests such aid.

"If there are requests on the part of the Americans, then we will surely participate," German Interior Minister Otto Schily told Reuters TV on Thursday. Schily said that in general, the United States is well equipped to deal with natural disasters and the geographic distance across the Atlantic Ocean may make it difficult to provide immediate assistance to the affected region along the Gulf Coast. Nevertheless, the Germans are willing to help though no request has been made, Schily said.

Through a statement released by the British Embassy, Queen Elizabeth II sent condolences.

"I was deeply shocked and saddened to learn of the deaths and injuries caused by Hurricane Katrina, and the scale of the damage and destruction now becoming apparent across the southern states," her Majesty said. "My sympathy goes to you and the people of the United States, especially to the families of those who have lost their lives, to the injured and to all who have been affected by this terrible disaster."

Later in the day, State Department spokesman Sean McCormack said as many as one dozen countries so far had offered to help the United States deal with the hurricane's aftermath.

"These offers of assistance are starting to come in," McCormack said. "We appreciate each and every one of them. And we are going to work in the coming days and weeks with foreign governments to see how we can best channel these offers of assistance with relation to what the needs are that are out there."

The embassy of Saudi Arabia said the kingdom stands ready to increase its oil production to 11 million barrels per day to compensate for the losses from Katrina, but Oil Minister Ali Al-Naimi said an adequate supply of crude is available in the United States where stocks are almost 40 million barrels more than last year at this time.

McCormack urged foreign nationals seeking news about relatives who may have been in the storm's path to first try to contact the family member directly and then to try the relevant embassy. He added that tens of thousands of passport applications in the works at the passport office in New Orleans, one of the nation's busiest passport centers, are trying to be preserved.

"Our Consular Affairs Bureau is working actively, and I think they started this effort even as early as yesterday to try to see what cases they have there electronically that they can work on and try to resolve those cases," he said. "And we're also working to redirect any traffic that might have otherwise gone to the New Orleans agency to other agencies."

Federal Responders Take Action

Several U.S. federal agencies have been activated to help out so far.

Transportation Department workers were ordered to help highways, airports, seaports and oil pipelines in the region. Generators were being moved to pipeline pumping stations to restore the flow of oil to the region.

Transportation Secretary Norm Mineta said that more than 400 trucks are mobilizing 5.4 million read-to-eat meals, 13.4 million liters of water, 3.4 million pounds of ice, 135,000 blankets, 11,000 cots, 200 tables and 450 chairs among other items.

The Pentagon sent four Navy ships from Hampton Roads to the Gulf of Mexico to help with hurricane relief efforts. They will join the U.S.S. Bataan, which was already in the Gulf for training. Two ships left Norfolk Thursday morning and two more headed out in the afternoon.

In addition, the hospital ship USNS Comfort was departing Baltimore for the Gulf region on Wednesday while eight swift water rescue teams from California headed to Louisiana to help pull stranded residents from their flooded homes and neighborhoods. The Army and Air Force were also providing search and rescue helicopters.

Assistant Defense Secretary Paul McHale said the National Guard is responding at the request of governors, but it's unlikely the president will call in active duty personnel military to restore order.

On arriving in Washington, Bush announced that he would open the Strategic Petroleum Reserve (search), an emergency stockpile of nearly 700 million barrels of oil stored in underground salt caverns along the Texas and Louisiana Gulf Coast. The reserve is designed to cushion oil markets during energy disruptions. Eight refineries were shut down due to Katrina — half of them producing gasoline.

Energy Secretary Samuel Bodman said that the reserves are given out on loan and the oil companies will replace the stockpiles once they are operating again at normal capacity.

"Technically it's called an exchange of oil that we deliver today and that we will get oil back plus some interest, if you will, in the future. We will be tapping that today," he said.

Oil refiners are in need of the oil because the Gulf supplies most of the nation's daily production. The loss of electricity has shut down power pipelines and drilling equipment. On Monday, Citgo Petroleum Corp. (search) asked for 250,000 to 500,000 barrels to ensure that its Lake Charles, La., refinery doesn't run out.

"There is an issue with respect to getting electrical power so that we can operate the various pipelines that supply fuel to the rest of the country," Bodman told another cable news channel.

"Our job is to get the infrastructure going again," Bodman said. "To the extent that we have delays in getting these pipelines functioning, then were are going to have the potential for gasoline shortages."

According to the New Orleans area power grid managers, it could take six to eight weeks for power to be restored in the New Orleans area, where one of the five SPR caverns is located. The power can't be restored until after the water is drained. After power is restored, water service can be re-established, the managers said.

Bodman said that his agency is keeping an eye out for price gouging. In some areas on Wednesday, gas prices had surpassed $3 per gallon, with rates rising as much as 40 cents per gallon overnight at some stations.

"I would like to believe that in this time of crisis that all of us are going to pull together to try to deal with this very difficult circumstance and situation that's confronting not just this region, but this country," he told FOX News. "We're hopeful of that, but if we have some bad actors, we have a mechanism to deal with it."

In addition to the reserve release, the Environmental Protection Agency announced it would temporarily allow the sale of higher-polluting gasoline in Alabama, Florida, Louisiana and Mississippi because those states can't provide enough fuel to consumers that meets Clean Air Act (search) requirements.

The agency also said those states will be allowed to use motor vehicle diesel fuel with a sulfur content higher than the 500 parts per million standard for the next two weeks through ozone season.

FOX News' Sharon Kehnemui Liss, Kelly Chernenkoff, Adam Housley and Teri Schultz and The Associated Press contributed to this report.