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Homeland Security Secretary Michael Chertoff defended his agency's response to Hurricane Katrina, saying Wednesday that the federal government paid close attention and quickly reacted to the disaster, despite some missteps.

"We were acutely aware of Katrina and the risk it posed," Chertoff told the Senate Homeland Security and Governmental Affairs Committee.

Amid a firestorm of criticism over the federal and local response to the disaster, Chertoff told lawmakers that the idea that the Bush administration in general or the Department of Homeland Security was detached from the storm or the needs of Gulf Coast residents is "simply not correct."

The secretary called the process of anticipating and dealing with consequences of Katrina "one of the most difficult and traumatic experiences of my life."

"You can't escape the fact when you talk about Katrina that this was a swarm of events of unprecedented magnitude," Chertoff said, noting that 90,000 square miles of land was impacted — an area larger than Great Britain — and more than 300,000 homes were destroyed.

On a good note, Chertoff said, the Coast Guard rescued 33,000 people, while the Federal Emergency Management Agency rescued more than 2,800. That total rescued by the two agencies is seven times higher than the number of people rescued in the seven hurricanes that hit Florida in 2004. Millions of meals and pounds of ice were also distributed, he noted.

Soon after Chertoff's testimony, the House Select Committee on Katrina issued its report sharply criticizing the federal response to the Aug. 29 disaster, which left more than 1,300 people dead, hundreds of thousands homeless and tens of billions of dollars worth of damage in its wake.

The Republican-dominated committee criticized everyone from President Bush to New Orleans Mayor Ray Nagin to the American Red Cross. Bush has accepted full responsibility for the federal government's shortfalls.

"Passivity did the most damage," concluded the 520-page report, titled "A Failure of Initiative." It says authorities failed to move even when they knew days in advance that the storm was reaching catastrophic strength.

"The failure of initiative cost lives, prolonged suffering, and left all Americans justifiably concerned our government is no better prepared to protect its people than it was before 9/11, even if we are," reads the report.

On the Senate side, committee Chairwoman Susan Collins, R-Maine, said in opening remarks that "within the federal government, DHS — which houses FEMA — bears the ultimate responsibility for a quick and effective response to disaster" yet the response was "time and again, late, uncertain and ineffective" and was "plagued by indecision and delay."

"If our government failed so utterly in preparing for and responding to a disaster that was long predicted and imminent for days, we must wonder how much more profound the failure would be if a disaster were to take us completely by surprise, such as a terrorist attack," she added.

"The chasm Katrina exposed between DHS and FEMA, one of its most important components, clearly presented one of the most significant impediments to a coordinated, swift federal response. Concerns about this disconnect were expressed long before Katrina, and our investigation has revealed disturbing conflicts over resources, roles and responsibilities."

The Louisiana congressional delegation, Gov. Kathleen Blanco, Nagin and other Louisiana officials were to hold a press conference at 3:45 p.m. EST. They are expected to address Chertoff's testimony, as well as a report released Wednesday by the House Select Committee on Katrina.

'FEMA Is a Four-Letter Word'

Sen. Joseph Lieberman, the ranking Democrat on the Senate Homeland Security and Governmental Affairs Committee, asked Chertoff why he did so little after becoming the department chief to ensure all agencies under his purview were ready to carry out their missions.

"How could you have left us with so many of those agencies so unprepared that when Katrina struck, too many of them ran around like Keystone Cops, uncertain about what they were supposed to do or unable to do it?" the Connecticut senator asked.

Chertoff said it was no secret that when he was confirmed, there was a lot of work to do to bring DHS agencies together, added that the agency was still finding its sea legs.

Sen. Mark Dayton, D-Minn., who noted that many properties in New Orleans still have no electricity and some businesses can't open their doors, added that FEMA is so ineffectual that perhaps Congress should consider rebuilding the agency altogether, and not just because of an insufficient response to this single incident.

"The problems in FEMA are so systemic and so ingrained, I frankly don't know — other than turning the responsibility over to the National Guard and making some chain of command temporarily responsible for emergencies until we can go back and start this agency all over again. It's so dysfunctional or non-functional, it's frightening," he said. "New Orleans is a macroexample, there are these smaller examples all over."

Added Sen. Norm Coleman, R-Minn.: "For many people, FEMA is a four-letter word, a negative four-letter word."

Sen. Trent Lott, who lost his Pascagoula, Miss., home in the storm, said he plans to introduce a bill this week to take FEMA out of DHS.

"I'm a victim of Katrina. My house is gone. My people have suffered mightily," said the Republican senator. "We're the turkeys who put FEMA into this behemoth and it was gobbled up. ...I think FEMA should be independent, Cabinet level ... report only to the disaster czar, the president of the United States."

House Report: Slow Response 'Prolonged Suffering'

In the report released Wednesday by the House Select Committee on Katrina, the federal government earns the majority of the blame for failing to take the reins and responding to the disaster in Louisiana and Mississippi, and to a lesser extent in Florida and Alabama.

Click here to read the report.

The committee, led by Rep. Tom Davis, R-Va., points out the levees that broke were designed to resist a Category 3 hurricane, but not the most severe storms. In the end, the levees didn't even live up to that standard.

"The single biggest failure of the federal response was that it failed to recognize the likely consequences of the approaching storm and mobilize federal assets for a post-storm evacuation of the flooded city," the report said. "If it had, then federal assistance would have arrived several days earlier."

The report also states the government's poor response caused loss of life, and "prolonged suffering and left all Americans justifiably concerned our government is no better to protect its people than it was before 9/11."

House Minority Leader Nancy Pelosi, D-Calif., called for an independent commission to probe the failures.

"Many more lives were lost, livelihoods are gone, housing has disappeared, and schools are unserviceable to children because of the inadequacy of the response. We will not know the whole story until we have an independent commission look at it," Pelosi said Wednesday. "We want to go forward. Only open government and honest leadership will take us there, but in addition to that, we must immediately in the right way meet the housing needs, health care needs, education needs and job needs of the people affected by Katrina and the other hurricanes."

Some lawmakers are calling on Chertoff to resign over his failure to oversee the federal response and take pre-emptive action to limit the damage. Collins said Wednesday she doesn't agree with that sentiment.

"The secretary is an enormously talented individual who has conceded the flaws in the response, and I believe that he's committed, committed beyond any other person in the federal government other than the president," Collins said after the hearing. "From my perspective it's very helpful to have him continue as secretary."

In Senate testimony last week, former FEMA Director Michael Brown singled out DHS as a muddled bureaucracy that slowed relief.

The White House and DHS note that Brown himself failed to follow a chain of command. E-mails released during the five-month investigation also suggest Brown was preoccupied with his appearance and publicity rather than an effective response. He has since resigned from his post.

Collins told Chertoff she remains "perplexed" about his decision to designate Brown as the point man for coordinating the government's response to the storm.

Chertoff said he had "no reason to doubt his commitment."

"If I knew then what I know now about Mr. Brown's agenda, I would have done something different," Chertoff added.

He repeated that he did not realize that levees in New Orleans had been breached on the day of the storm, despite Brown's claims to the contrary.

"When I went to bed, it was my belief ... that actually the storm had not done the worst that could be imagined," Chertoff said.

Collins told Chertoff that he "did seem curiously disengaged to me" when he attended at conference on bird flu in Atlanta on Aug. 30, instead of rushing to the storm scene.

Meanwhile, lawmakers are reviewing what happened to 11,000 trailer homes provided by FEMA that are meant to provide housing to 12,000 storm victims but are sitting unoccupied in Arkansas.

One DHS official said the trailers are in poor shape, sinking in the mud in a cow pasture. FEMA spokeswoman Nicol Andrews said the homes are habitable and ready for residency, but the problem is that no community in Louisiana has been located to accommodate the new neighborhoods that will be formed.

"FEMA mobile homes staged in Arkansas are habitable, available and properly maintained. They have not been damaged, and certainly none are being destroyed. Mobile homes are an important part of a comprehensive housing strategy, and are commonly used for temporary housing outside of floodplains," Andrews said in a written statement.

"We had hoped for a better reception in the state of Louisiana, in particular, for mobile home parks to be located in those parishes outside floodplains, but we continue to await the needed authorities to move them in. We expect to use these mobile homes in other open or future disasters," she added.

FEMA Acting Director David Paulison told FOX News that some Louisiana parishes are resisting the idea of trailer park communities. He added that FEMA would rather use travel trailers that cost less and can be placed in flood zones, which currently is prohibited for mobile homes.

The House Katrina report also blames state and local officials for waiting too long to order evacuations. Despite warnings of Katrina's potential destruction 56 hours ahead of landfall, the evacuation order came only 19 hours before Katrina hit.

"None of this had to happen," investigators concluded. "Despite years of recognition of the threat that was to materialize in Hurricane Katrina, no one — not the federal government, not the state government, and not the local government — seems to have planned for an evacuation of the city from flooding through breached levees."

The report found that charitable organizations such as the American Red Cross were overwhelmed by the sheer size of demands, leading to water, food and other supply shortages and disorganized sheltering processes.

Some of the response failures dated back to months and even years before Katrina hit. A lack of warning systems for levee failures delayed their fast repair and poor communications equipment prevented federal, state and local emergency responders from coordinating their counterattack.

Moreover, lessons learned from Hurricane Pam — a fictional storm designed to test Gulf Coast preparedness — went unheeded even though officials knew of the dangers that a Category 4 or 5 hurricane would pose to New Orleans.

House Democrats initially refused to participate in the committee, arguing that they believed it would try to spare the administration from criticism. But two Louisiana lawmakers, Reps. Charlie Melancon and William Jefferson of Louisiana, did participate. They wrote in a 59-page minority report that they agreed with many of the conclusions, but despite the panel's investigation, the committee "adopted an approach that largely eschews direct accountability.

Click here to read the minority report.

"The majority report rarely assesses how these problems occurred, why they were not corrected sooner, and who in particular was responsible," they wrote.

FOX News' Liza Porteus, Kelly Wright and The Associated Press contributed to this report.