Hurricane Ike slammed the Texas and Louisiana coast on Saturday with ferocious winds and a wall of water that flooded hundreds of miles, cut power to millions and caused billions of dollars in damage.
But relieved officials said Ike may not have caused the catastrophe that had been feared.
The storm, which idled about a quarter of U.S. energy production, smashed over the barrier island city of Galveston and paralyzed Houston, the country's fourth-largest city, shattering skyscraper windows and showering streets with debris.
There were unconfirmed reporters of "a few deaths," from Ike, Homeland Security Secretary Michael Chertoff said. He cited "significant surges" -- high seas pushed ashore by hurricanes -- and damage in Texas and Louisiana.
"We have already heard some initial reports of a few deaths. Obviously one death is more than we want to hear about," he told a news conference in Washington.
The Galveston and Houston ship channels were not hit as hard as expected.
"Fortunately the worst case scenario that was spoken about, that was projected in some areas did not occur," Texas Gov. Rick Perry told a briefing in Austin, Texas, although he said there had been "very heavy damage" to the power grid due to Ike.
Ike came ashore at Galveston as a strong Category 2 storm at 8:10 a.m. British time with heavy rains and sustained 110 mph (175 kph) winds, the National Hurricane Centre said.
It had weakened to a tropical storm by mid-afternoon as it barrelled 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, and it was not clear yet if all those who stayed had survived.
Chertoff refused to say whether he expected the death toll to rise. "I don't want to speculate," he said.
"If someone stayed in an area predicted to be largely flooded, they put their lives at risk."
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 may have been spared the worst of the flooding.
The storm's wide span meant it flooded parts of Louisiana, prompting a flurry of overnight rescues far from its centre, authorities said.
Ike could lead to $8 billion to $18 billion in insurance claims, according to an early insurance industry computer-modelled estimate of damage, Reuters reported.