The deaths and suffering of thousands of Hurricane Katrina's victims might have been avoided if the government had heeded lessons from the 2001 terror attacks and taken a proactive stance toward disaster preparedness, a House inquiry concludes.

But from President Bush on down to local officials there was largely a reactive posture to the catastrophic Aug. 29 storm — even when faced with early warnings about its deadly potential.

A 520-page report, titled "A Failure of Initiative," was being released Wednesday as Homeland Security Secretary Michael Chertoff testifies before a Senate committee conducting a separate investigation of the government's Katrina response.

The Associated Press obtained a copy of the report Tuesday night.

"The preparation for and response to Hurricane Katrina should disturb all Americans," said the report, written by a Republican-dominated special House committee chaired by Rep. Tom Davis, R-Va.

"Passivity did the most damage," it said. "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."

The hard-hitting findings allocated blame to state and local authorities and concluded that the federal government's single largest failure was in not recognizing Katrina's likely consequences as it approached. That could have prompted a mobilization of federal assets for a post-storm evacuation of a flooded New Orleans, the report said, meaning aid "would have arrived several days earlier."

It also found that Bush could have speeded the response by becoming involved in the crisis earlier and says he was not receiving guidance from a disaster specialist who would have understood the scope of the storm's destruction.

"Earlier presidential involvement might have resulted in a more effective response," the inquiry concluded.

White House spokesman Allen Abney declined to comment Tuesday night. On Monday, White House homeland security adviser Frances Fragos Townsend said Bush was "fully involved" in Washington's preparations and response to Katrina.

The inquiry into one of the nation's worst natural disasters looked at everything from the evacuation to the military's role to planning for emergency supplies and in each category found much to criticize. The House study is the first to be completed in a series of inquiries by Congress and the Bush administration into the massive failures exposed by Katrina.

Katrina left more than 1,300 people dead in Louisiana, Mississippi and Alabama, hundreds of thousands homeless and tens of billions of dollars worth of damage. Bush has accepted responsibility for the federal government's shortfalls, but the storm response continues to generate finger-pointing.

House Democrats who participated in the inquiry could not immediately be reached for comment Tuesday night. But in a 59-page response released last Sunday, Reps. Charlie Melancon and William Jefferson of Louisiana said that while they largely agreed with its conclusions, the report falls short of holding "anyone accountable for these failures."

Despite its accomplishments, the committee "adopted an approach that largely eschews direct accountability," Melancon and Jefferson said in their assessment.

The report finds fault with Chertoff for failing to activate a national plan to trigger fast relief, and with Homeland Security for overseeing a bare-bones and inexperienced emergency response staff. It found that the military played an invaluable role in the response but lacked coordination with Homeland Security and other relief agencies.

Moreover, federal agencies were unclear about their responsibilities under a national response plan issued a year ago. And lessons learned from Hurricane Pam — a fictional storm designed to test Gulf Coast preparedness — went unheeded.

Describing similar delays, the report concludes that Louisiana Gov. Kathleen Blanco and New Orleans Mayor Ray Nagin waited until too late to order a mandatory evacuation of the city. Despite warnings of Katrina's potential destruction 56 hours ahead of landfall, the evacuation order came only 19 hours before Katrina hit.

Charitable organizations such as the American Red Cross were described as overwhelmed by the sheer size of demands, leading to water, food and other supply shortages and disorganized sheltering processes.

The House panel spent five months investigating the failures. It interviewed scores of federal, state and local authorities, sorted through more than 500,000 pages of e-mails, memos and other documents and held nine public hearings spotlighting sometimes feeble explanations by officials.

Though some Democrats — mostly representing Gulf Coast districts — participated in the House inquiry, their party leaders boycotted it, holding out for an independent commission similar to the one that investigated the Sept. 11, 2001, attacks.