Lawmakers promised Friday that a $10.5 billion measure funding immediate rescue and relief efforts for victims of Hurricane Katrina (search) would be but the first step toward a comprehensive response by Congress to the catastrophe.

The bill advanced amid widespread complaints among members of Congress that the government's rescue effort has been inadequate. Lawmakers also promised oversight hearings into flawed disaster plans and the government's slower-than-hoped response.

"We have to ask ourselves ... how could things have been different?" said House Minority Leader Nancy Pelosi (search), D-Calif. "What could have been done to prevent the magnitude of this tragedy? These are questions that Congress should legitimately ask."

The relief bill passed the House by voice vote after Senate approval late Thursday. It comes as the Federal Emergency Management Agency (search), the government's front-line responder in natural disasters, is spending more than $500 million a day on Katrina.

The new aid averts the possibility that money might run out before Congress reconvenes on Tuesday.

House Majority Leader Tom DeLay (search), R-Texas, said the bill was only the first step toward a "comprehensive, long-term response to the Katrina disaster." He promised Congress would provide more humanitarian aid, combat gasoline price gouging, provide assistance to businesses and the unemployed, rebuild infrastructure and utility systems, and help local law enforcement.

"Make no mistake, this $10.5 billion is initial relief," DeLay said. But it was too early to say exactly what further steps Congress might take to help the situation along the Gulf Coast — or make sure future disaster response efforts go more smoothly.

Lawmakers also promised hearings into gasoline prices and the adequacy of preparations by the federal and state governments for such a disaster.

"We need to understand from the key authorities what went wrong, what should have been done, and, most importantly, what needs to be done so we're ready next time," said Sen. Jon Kyl, R-Ariz.

President Bush welcomed Congress' quick action on his request for an infusion of funds.

"I want to thank the Congress for acting as quickly as you did," Bush said of the $10.5 billion measure, which he signed into law later Friday. "But I've got go to warn everybody that's just the beginning."

Frustration with the rescue effort — and the continued lack of help for many of the mostly poor and black victims in New Orleans — reached a boil as the Congressional Black Caucus blasted Bush's handling of the crisis.

"I'm ashamed of America. I'm ashamed of our government," said Rep. Carolyn Kilpatrick, D-Mich. "I'm outraged by the lack of response by our federal government."

"Last year, when the president's election was in question, his response to the hurricanes in the swing state of Florida was tremendously fast," said Rep. Robert Wexler, D-Fla. "Where was he in the immediate aftermath for the Gulf Coast? Where were the trucks of food?"

The bill combines $10 billion in new FEMA funds — enough to last just a few weeks — and $500 million for the Pentagon's role in the relief mission.

The FEMA funds, among other uses, will finance food and emergency shelter, medical care, debris removal, generators and cash payments to hurricane victims. FEMA will also funnel funds to other federal agencies such as the Army Corps of Engineers, responsible for repairing levees around New Orleans and pumping out the flood waters inundating the city.

Long-term costs were anyone's guess. It could be months before New Orleans is cleared of flood waters, and until then, it's impossible to determine long-term needs. Many areas along the coast have yet to receive visits from federal officials.

Apart from the formal aid provided by Congress, one lawmaker decided to volunteer his personal labor to the relief effort.

Majority Leader Bill Frist, R-Tenn., a surgeon before entering the Senate, arranged to spend the weekend in the storm-damaged area as a medical volunteer, according to one aide.

Few lawmakers trekked to Washington for the brief House debate. Among those absent from the House session was Speaker Dennis Hastert, R-Ill., who attracted criticism Thursday for telling the Daily Herald, a suburban Chicago paper, that he wasn't sure whether it makes sense to spend billions rebuilding a city that lies below sea level, a reference to New Orleans. He subsequently clarified his remarks.

Hastert was in Indiana on Friday morning at a fundraiser for Rep. Mark Souder, R-Ind. He then attended a charity auction for hurricane victims, donating a Lincoln Continental to help raise money, an aide said.