Already a killer storm, Irene sloshed through the New York metropolitan area Sunday, briefly flooding parts of the city and severing power to a million people but not provoking the doomsday urban disaster that had been feared.

Diminished to a tropical storm and racing to its own overnight demise in New England and Canada, Irene killed at least 18 people in six states. More than 4.5 million customers lost power along the East Coast and well inland. Initial property damage estimates ranged up to $7 billion.

And it was not over yet.

“Many Americans are still at serious risk of power outages and flooding, which could get worse in coming days as rivers swell past their banks…,” President Barack Obama said Sunday evening. “There are a lot of communities that are still being affected.”

Irene dumped immense amounts of rain on a region already saturated by summer downpours. Many communities in Pennsylvania, New Jersey, upstate New York, Connecticut, Vermont and elsewhere endured life-threatening floods and toppling trees.

State and local authorities warned of more to come and they begged residents not to become complacent. It takes some time for rain runoff to accumulate, they said, tree roots were weakening in the over-moist soil and the danger will not end for days.

“Stay inside,” Gov. Chris Christie told New Jersey residents. “The real issue that we’re going to have to deal with now is flooding. We’re going to experience major flooding. Some rivers haven’t crested yet, and it’s still raining.”

Christie noted at least 300 road closures and obstructions across his state, though he said the New Jersey Turnpike and bridges were clear, so tree-clearing equipment was on its way. Deep floods swamped portions of Hackensack, Westwood, Ridgewood, Hillsdale and other communities in New Jersey.

In New York City, ocean water invaded some beachside communities, and both the East River and the Hudson River overtopped their banks, but the resulting floods were not major and most receded quickly. At the same time, numerous waterborne rescues were necessary in Staten Island, Westchester County and other parts of the area.

“It was pretty scary at four in the morning when I was woken up by the wind, but other than that, things don’t seem so bad,” said Nora Flaherty of Brooklyn. “I’m glad people took this seriously. Better safe than sorry.”

By midday, with the rain coming to an end, she and many other New Yorkers ventured outside to inspect their surroundings and walk their dogs.

In the Clinton Hill area near Brooklyn Heights, little damage was evident, though the basement of some brownstone townhouses flooded. Residents reported two to three inches of water in their apartments, saying there would have been more if they hadn't created sandbag dams at the entrances.

Young children in raincoats and boots stomped through puddles, laughing as they were blown about in the wind, and life began returning to normal in other ways. The New York Stock Exchange planned to open for business as usual Monday and, consequently, the Men’s Wearhouse store near Wall Street swiftly re-opened for business Sunday.

“The city and the state did a phenomenal job of getting everyone ready and were very forceful in terms of recommending evacuations, especially from the low-lying areas – I’m very happy about that,” said Scott Schoneman, a New York resident who works in the financial industry. “And the storm itself, it didn’t seem to be as bad as they were predicting.”