A weakening Hurricane Katrina battered the Gulf Coast from Louisiana to the Florida Panhandle Monday, but spared New Orleans the devastating direct hit that had been widely feared and that prompted the mandatory evacuation of the city.

Although its wind speed dropped as it made landfall shortly after 7 a.m. EDT, the hurricane still packed enough power to cause widespread wind damage and to flood neighborhoods in Louisiana, Mississippi and Alabama. It also tore away about half the outer covering of the roof of the Superdome, a 65,000-seat stadium that was turned into a refuge of last resort for nearly 10,000 people who were unable to evacuate New Orleans.

Some of the worst damage was reported from the city's outlying parishes and from points farther east along the coast of Mississippi, where the storm wrecked numerous buildings, flooded streets and heaved boats onto land.

Near Lake Ponchartrain, floodwaters unleashed by Katrina lapped at the rooflines of one-story homes, trapping a number of people in attics or on rooftops. In St. Bernard parish just east of New Orleans, an estimated 40,000 homes were flooded.

Gulfport, Miss., was hit hard by the hurricane, with reports of buildings collapsing and floodwaters up to 10 feet or higher in some places.

"I've been out there," Gulfport Fire Chief Pat Sullivan said, the Associated Press reported. "It's complete devastation."

Mississippi Gov. Haley Barbour (R) said his state was struck "like a ton of bricks" and that his worst fear was "a lot of dead people down there" on the coast.

"We know some people got trapped, and we pray they are okay," Barbour told reporters.

It was not immediately clear whether any people had been killed by the flooding or building collapses Monday. Officials said rescue teams had yet to reach some of the hardest-hit areas. In Alabama, two persons were reported killed in a vehicle wreck attributed to Katrina's heavy rains, and three elderly people were said to have died while being evacuated from a New Orleans nursing home to a church in Baton Rouge.

Last week, Katrina was blamed for at least nine deaths as it cut across the southern tip of Florida.

On the Mississippi coast, major flooding was reported in Bay St. Louis and East Biloxi, and the Biloxi River was flowing over a bridge on Interstate 10. In Gulfport, three fire stations sustained significant damage, and a grade school collapsed. Roofs reportedly were torn off several schools and government buildings in Harrison County and Pascagoula. Several casinos on the Mississippi seafront were also reported flooded.

In the renowned French Quarter of New Orleans, a city of 485,000 people, the streets were littered with debris, and water had gathered in some places. But there was no sign of the major flooding that authorities had feared.

The city's protective levees appeared to have held for the most part. One levee on the Industrial Canal was reported broken, but it was not considered a major problem.

Of potentially greater concern was the fate of a couple of hundred oil and gas rigs and platforms in the Gulf waters off Louisiana. They were believed to have borne the brunt of Katrina when it was at its most powerful on Sunday, and significant damage was feared from the high winds and huge waves.

"Katrina is by no means over," Louisiana Gov. Kathleen Babineaux Blanco (D) told a late afternoon news conference. She said several outlying parishes in the New Orleans area were devastated and urged residents who evacuated to stay away, allowing emergency workers to do their jobs.

"High water and strong winds are making it too dangerous for emergency workers to reach some of these areas at this time," she said. "Wherever you live, it is still too dangerous for people to return home. . . . The roads are flooded, the power is out, the phones are down, and there is no food or water, and many trees are down." So private vehicles may not be able to get through anyway, she said.

"Our Gulf Coast is getting hit and hit hard," President Bush said during a visit to El Mirage, Ariz. "I want the folks there on the Gulf Coast to know that the federal government is prepared to help you when the storm passes. . . . In the meantime, America will pray . . . for the health and safety of all our citizens." He urged people not to abandon their shelters.

Bush issued "major disaster" declarations for Louisiana and Mississippi, making the states eligible for prompt and extensive federal aid.

Katrina, which strengthened to a Category 5 storm with winds up to 175 mph Sunday as it bore down on the coast from the Gulf of Mexico, made landfall as a Category 4 storm after weakening overnight. It smacked ashore with winds of about 140 miles an hour, but four hours later the National Weather Service downgraded it to a Category 3 storm packing sustained winds near 125 mph. By 3 p.m. EDT, Katrina was down to a Category 1 hurricane with maximum winds of 95 mph. Two hours later, its winds had slowed to 75 mph, and further weakening was forecast as it made its way north.

The weather service said earlier that storm surge flooding from Katrina in the greater New Orleans area could reach 10 to 15 feet, a level near the tops of the levees that protect the city, much of which lies below sea level.

But officials said the levees appeared to be holding, with New Orleans apparently spared the storm surges of up to 28 feet that threatened to overwhelm the levees and deliver the massive destruction that residents have long feared.

"Significant storm surge flooding is occurring elsewhere along the central and northeastern Gulf of Mexico coast," the National Weather Service said.

"Nothing we know of yet has imperiled the lives of large numbers of people," Louisiana Gov. Blanco said in a televised news conference Monday morning.

She played down damage to the Superdome, where hurricane winds ripped off some of the outer skin of the vast roof and punched a couple of small holes through it, allowing rain water to leak onto some of the refugees encamped on the stadium's football field below.

"Right now there is no real structural damage that is obvious in the Superdome," Blanco said, citing a report from a National Guard civil engineer. She said it was "only the fabric over the structure" that tore off and that Katrina did not cause a "structural failure" of the roof itself. The roof covers 9.7 acres and is held up by steel beams.

Blanco later told reporters that she had received reports that a couple of people had died of heart attacks and that one employee of the Federal Emergency Management Agency [FEMA] had been killed in a vehicle crash in Alabama while en route to Louisiana.

Blanco said St. Bernard and Plaquemines parishes southeast of New Orleans appeared to have been the hardest hit in Louisiana, and there were reports of about 100 people stranded on roofs awaiting rescue from flooding.

She said that about 20 residential and commercial buildings reportedly collapsed in the New Orleans area but that it was difficult to get specific information.

"We can't even send anybody out at the moment," Blanco said. "We don't know what the worst is right now."

The area around the Superdome was strafed by the high winds, which blew out windows in four high-rise buildings nearby, leaving blinds and curtains flapping in the gusts and rain. On one side of the Hyatt Regency Hotel in New Orleans, almost all the windows were broken.

The city's Canal Street was virtually impassible from fallen palm trees, toppled awnings and other debris.

"I thought it was going to be a lot worse," said Dusty Post, 52, of Nashville, Tenn., who rode out the storm at the Fairmont Hotel. Her friend Jo Hardeman, 53, also of Nashville, said, "We prayed and sang and read the word, and God was with us."

As the center of the hurricane passed over the area, a FEMA disaster inspector said on CNN that Katrina "was not as bad a predicted" in metropolitan New Orleans.

"We do not have significant structural damage," said Mike Majonos from his home in Metairie, just west of the city. He said New Orleans was not experiencing a storm surge, but some fresh-water flooding from Katrina's torrential rains.

"The levees will hold," Majonos said. "The main hurricane levee system in the metropolitan area will probably hold, but we have a creeping fresh-water flooding problem."

The Weather Service said Katrina's center was about 30 miles northwest of Laurel, Miss., by 5 p.m. EDT and moving north at about 18 mph on a track forecast to take it into central and northern Mississippi Monday night.

As it hit the coast, hurricane-force winds extended outward up to 125 miles from the center, the Weather Service said.

The storm made landfall at 7:10 a.m. EDT near the bayou town of Buras about 63 miles southeast of New Orleans.

The storm left nearly 1 million people without power from Louisiana to the Florida Panhandle.

Windows were blown out at some New Orleans hotels, and guests were told to go into interior hallways and use blankets and pillows to protect themselves from flying glass.

On the southern shore of Lake Ponchartrain, entire neighborhoods of one-story, shotgun-style homes were flooded up to the rooflines, the Associated Press reported. On one roof, two stranded people yelled for help as murky water lapped at the gutters.

"Get us a boat!" a man in a black slicker shouted over the howling winds, AP reported.

Across the street, a woman shouted for assistance from the second-story window of her brick home. "There are three kids in here," the woman said. "Can you help us?"

In suburban Jefferson Parish, Sheriff Harry Lee said residents of a building on the west bank of the Mississippi River called 911 to say the building had collapsed and people might be trapped, AP reported. He said deputies were not immediately able to check out the building because their vehicles were unable to reach the scene.

In Lafayette, La., Nelson Robinson, a weather consultant for oil companies operating in the Gulf, said the companies on Friday started evacuating many of the 30,000 to 40,000 people who work on the rigs and platforms. He projected extreme damage along a 40-mile-wide swath of the Gulf because of massive waves churned up by the hurricane.

Robinson estimated that waves near the Katrina's eyewall could have topped 98 feet Sunday, exceeding by a couple of feet the height of the waves that Hurricane Ivan unleashed last year. Ivan caused major damage to oil operations in the Gulf, and some of the rigs and platforms had only recently been repaired.

Some of the oil rigs operate as far as 200 miles off the coast in 10,000 feet of water.

Robinson said oil companies planned to send crews out Tuesday at first light to assess the damage.

With Katrina bearing down on his city Sunday, New Orleans Mayor Ray Nagin ordered the mandatory evacuation of its civilian population, but officials acknowledged that tens of thousands of residents and tourists would be unable to leave. With the airport closed, the city organized buses to transport those left behind to 10 emergency shelters, including the Superdome, and encouraged people to bring supplies and food for a three- to five-day stay. Three nursing home patients died during the evacuation, according to an AP report.

Katrina formed last Wednesday over the Bahamas as a tropical depression. By Thursday it was a Category 1 hurricane with 80-mph winds, flooding neighborhoods in South Florida and leaving more than 1 million homes and businesses without electricity. The storm then moved over the Gulf of Mexico and, nourished by warm waters, angled toward the Gulf Coast as it steadily rose in intensity.

Moreno reported from Louisiana, and Branigin reported from Washington. Staff writer Fred Barbash contributed to this report.