* Ike pummels Texas, damage less than feared

* No confirmed deaths, 4.5 million lose electricity

* At least $8 billion in insured losses estimated

* Refineries closed, but no major damage reported

By Chris Baltimore and Anna Driver

HOUSTON, Sept 13 (Reuters) - Hurricane Ike slammed into the most populated part of the Texas coast on Saturday with ferocious winds and a wall of water that flooded seaside towns, paralyzed the oil hub of Houston and cut power to millions.

Although Ike is believed to have inflicted billions of dollars in damage, relieved officials and residents said the monster storm the size of Texas appears to have been less destructive than originally feared.

The hurricane, which idled about a quarter of U.S. crude oil production and refining capacity, swamped the island city of Galveston and then hammered Houston, the country's fourth-largest city, shattering the windows of skyscrapers and showering streets with debris.

Homeland Security Secretary Michael Chertoff said he had no confirmation of any storm-related deaths, but there were concerns that rescuers could still find people who did not evacuate, buried in rubble.

"We hope for the best, but I do want to prepare people for the fact that there may be some fatalities," Chertoff said in the state capital, Austin, before visiting the storm area.

Galveston and the Houston Ship Channel were not hit as hard as expected. Emergency officials had predicted a 20-foot (six-metre) storm surge that could have caused far greater damage and swamped refineries.

"Fortunately the worst case scenario that was spoken about, that was projected in some areas, did not occur," said Texas Gov. Rick Perry.

He noted, however, "very heavy damage" to the power grid. About 4.5 million people could face weeks of power outages.

Ike came ashore at Galveston as a strong Category 2 storm early on Saturday with heavy rains and sustained winds of 110 mph (175 kph), the National Hurricane Center said.

It had weakened to a tropical storm by mid-afternoon as it barreled northward on a path expected to bring heavy rains across a swath of the country stretching to Canada.

The storm flooded Galveston, sending waves over a 17-foot (5-metre) sea wall built to protect the city after a 1900 hurricane killed at least 8,000 people.

More than half the city's 60,000 residents fled before the storm. It was not clear how bad the damage was in Galveston, but the first aerial pictures showed homes surrounded by sea water.

Galveston City Manager Steve LeBlanc said 17 buildings had collapsed on the historic island, a favorite for beach-loving Texans, and the causeway linking to the mainland had buckled.

FRANTIC RESCUE CALLS

In Bridge City, a small community along the upper Texas coast, frantic calls for rescue overwhelmed emergency workers.

"We just received one call from a guy in his attic and the water is rising and he can't get out," said Orange County spokeswoman Jill Frillou. "There were a lot of people that did not leave and just did not expect water to come that high."

Ike triggered the biggest disruption to U.S. energy supplies in at least three years and sent gasoline prices higher at the pumps.

Oil refineries along the western shore of Galveston Bay and Port Arthur may have been spared the worst of the flooding, said Brad Penisson, a spokesman for the joint operations of southeast Texas emergency management agencies.

At NASA's Johnson Space Center, there was no major flooding but a portion of the Mission Control Center roof was damaged. All systems supporting the International Space Station were functioning normally, the agency said.

Ike could lead to $8 billion to $18 billion in insurance claims, according to an early computer-model estimate of damage by the industry.

The storm was the biggest to hit a U.S. city since Hurricane Katrina devastated New Orleans in 2005.

Houston is home to 2.2 million people and a metropolitan area of 5.6 million residents. Unlike much of the United States, it has a booming economy thanks to demand for energy.

It was not clear if Houston would resume business -- including its big energy trading operations -- by Monday. But the hurricane delayed major sporting events, like a much awaited set of games for the Houston Astros baseball team.

Officials could hardly conceal their relief although most of Houston lacked power and clean water. "It's been miraculous in many ways," said Harris County Judge Ed Emmett. "The truth of the matter is, we have survived."

Authorities were cautious, however, about early confidence over the limited damage, especially after the Katrina experience, when levees broke under the floodwaters long after the storm.

President George W. Bush, who was strongly criticized for the slow federal response to Katrina, declared a major disaster in his native Texas and in Louisiana, and ordered federal aid to supplement state and local efforts in the storm area.

Ike also flooded coastal communities and forced rescuers out to save stranded residents in parts of Louisiana. (Additional reporting by Tim Gaynor in League City; Eileen O'Grady, Erwin Seba and Bruce Nichols in Houston and Jim Forsyth in San Antonio; Richard Cowan and Matt Spetalnick in Washington; Carey Gillam in Kansas City, Jessica Rinaldi in Galveston, and Lilla Zuill and Richard Valdmanis in New York; Writing by Mary Milliken; Editing by Chris Wilson)

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