By Marc Caputo, David Ovalle, Erika Bolstad and Martin Merzer,Knight Ridder Newspapers

NEW ORLEANS – At least 55 people died, floods engulfed thousands of homes and shell shocked survivors retreated to attics and wind-blown roofs Monday as one of the most sweeping hurricane disasters of modern times ravaged the upper Gulf Coast.

Authorities in Mississippi blamed Hurricane Katrina for 50 deaths in the Gulfport and Biloxi area. Two people died in Alabama and at least three bodies were seen in New Orleans.

The casualty toll seemed certain to mount as conditions improved and rescue workers in boats and helicopters searched through the night and after daybreak today for victims.

In another measure of human misery, tens of thousands of people will need temporary housing for months, Michael Brown, director of the Federal Emergency Management Agency, said Monday night.

“I’ve never been so scared,” one of the newly displaced, Jean Jenkins of Moss Point, Miss., said after she, her husband, their two dogs and a cat spent seven hours in the attic of their one-story house before the water receded just enough for them to leave.

Katrina weakened slightly and wobbled toward the east just before reaching land, sparing New Orleans the cataclysmic devastation many had feared. But, most agreed, it was more than bad enough there and truly disastrous in parts of Mississippi and Alabama.

“We didn’t know if we were going to live,” said Diana Chavez, one of 10,000 people who spent the night at the Superdome, a refuge of last resort that lost part of its roof.

Katrina’s core roared very close to the below-sea-level city of 485,000 people, slamming eastern sections with one edge of its destructive eye wall. Winds of 100 mph rocked the area.

Its storm surge and torrential rain submerged vast areas, with 40,000 homes flooded in St. Bernard Parish alone.

Moreover, the storm’s sphere of misery stretched from central Louisiana on the west to the Florida Panhandle on the east.

Triple-digit wind gusts were reported in Mississippi and Alabama. Damage reports mounted throughout the region: swamped bridges, overrun beaches, boats hurled ashore, countless smashed windows and ripped roofs.

Katrina pummeled 270 miles of coastline across four states, striking particularly hard at Gulfport, Miss.

Pat Sullivan, Gulfport’s fire chief, said downtown buildings were “imploding” and the business district was largely under water. A section of Interstate 10 near Gulfport was washed away. “It’s complete devastation,” Sullivan said.

More bad news: Late Monday, the first hard evidence emerged of possible gasoline supply disruptions. Valero Energy Corp. said its giant St. Charles, La., refinery was flooded, powerless and shut for at least a week.

About 1.3 million customers in the region were without power.

New Orleans Mayor C. Ray Nagin said that at least 20 buildings collapsed, including a small apartment complex. Countless windows shattered in high-rise buildings, the curtains of hotel rooms billowing in the wind.

Floodwaters breached at least two of the city’s crucial flood-control levees, Nagin said, and three pumps failed. Portions of the historic, tourist-heavy French Quarter were battered, but little flooding was seen and the area fared reasonably well.

Hours after the storm hit, about 200 people remained atop their roofs in New Orleans East and the Lower Ninth Ward, driven there by 10-foot floods.

Nagin said he was grateful the damage wasn’t even worse, but he pleaded with residents not to return prematurely to whatever was left of their homes.

“Please be patient,” he said. “There’s nothing for you to come back to right now. There’s water everywhere. … When are we going to get life back to normal? I don’t know.”

New Orleans Police Superintendent Eddie Compass said three people were arrested for looting.

The city of Gulfport, 55 miles northeast of New Orleans and nearly under the storm’s eye wall, suffered particularly severe blows.

Hospitals sustained heavy damage, sailboats floated in the middle of U.S. 90, and casinos in the area were said to be deeply flooded.

Along the Mississippi coast, a 28-foot storm surge – the wall of water that accompanies the center of a hurricane – knocked homes and other buildings from their foundations. People trapped in attics and roofs begged for rescue but had to wait hours for assistance.

“We know some people got trapped and we pray they are OK,” said Mississippi Gov. Haley Barbour.

In Biloxi, 6 feet of water blocked Interstate 10 at the Biloxi River and local casinos were flooded. The Hard Rock Casino, scheduled to open next week, was extensively damaged. A church in nearby Long Beach was destroyed, as was the harbor.

In downtown Mobile, Ala., 12 feet of water flooded the convention center, the state docks, the metro jail, which had been evacuated, and dozens of other downtown structures. Whitecaps surged down Water Street.

Emergency workers helped “dozens and dozens” of people who called during the storm to say water was rising into their homes, said Mobile police officer Eric Gallichant. “Unfortunately there were some people it was impossible to get to,” he said.

A relatively small and weak hurricane when it rolled through South Florida late last week and killed nine people, Katrina blossomed into one for the record books after it reached the Gulf of Mexico and turned north.

Its core made landfall almost directly south of New Orleans as a monstrous Category 4 hurricane with 145-mph wind.

It weakened steadily as it moved inland but remained extremely dangerous, according to the National Hurricane Center, which warned of 10 inches of rain over the Ohio Valley and the manifest dangers of inland flooding as far north as Ohio.

When the storm’s center reached land, its hurricane winds of at least 74 mph reached 125 miles from the center and its tropical storm winds of at least 39 mph stretched 270 miles from the center.

Back in New Orleans, the Hyatt Regency hotel near the Superdome reported windows and doors blown out and the walls buckled on the 22nd floor.

Hundreds of Hyatt guests and storm refugees were evacuated out of their rooms around midnight to a third-floor ballroom. They rested on bedspreads and pillows they dragged down from their hotel rooms. Children cried, dogs barked.

David Hadley, 43, of Chalmette, La., tried to stay in his room.

“The walls were shaking, the lamp was shaking like it was “Poltergeist,’ then the glass on the window started to crack. It made an “Eeeeh-eeeeh’ sound,” Hadley said. “It wasn’t nothin’ nice. I got outta there.”