SOUTH WINDSOR, Conn. — When winter’s white mixes with autumn’s orange and gold, nature gets ugly.

A freak October nor’easter knocked out power to more than 3 million homes and businesses across the Northeast on Sunday in large part because leaves still on the trees caught more snow, overloading branches that snapped and wreaked havoc. Close to 2 feet of snow fell in some areas over the weekend, and it was particularly wet and heavy, making the storm even more damaging.

“You just have absolute tree carnage with this heavy snow just straining the branches,” said National Weather Service spokesman Chris Vaccaro.

From Maryland to Maine, officials said it would take days to restore electricity, even though the snow ended Sunday.

The storm smashed record snowfall totals for October and worsened as it moved north. Communities in western Massachusetts were among the hardest hit. Snowfall totals topped 27 inches in Plainfield, and nearby Windsor had gotten 26 inches by early Sunday.

It was blamed for at least nine deaths, and states of emergency were declared in New Jersey, Connecticut, Massachusetts and parts of New York.

Roads, rails and airline flights were knocked out, and passengers on a JetBlue flight were stuck on a plane in Hartford, Conn., for more than seven hours. And while children across the region were thrilled to see snow so early, it also complicated many of their Halloween plans.

More than 800,000 power customers were without electricity in Connecticut alone — shattering the record set just two months ago by Hurricane Irene. Massachusetts had more than 600,000 outages, and so did New Jersey — including Gov. Chris Christie’s house. Parts of Pennsylvania, New Hampshire, New York, Maine, Maryland and Vermont also were without power.

“It’s going to be a more difficult situation than we experienced in Irene,” Connecticut Gov. Dannel P. Malloy said. “We are expecting extensive and long-term power outages.”

Thirty-two shelters were open around the state, and Malloy asked volunteer fire departments to allow people in for warmth and showers. At least four hospitals were relying on generators for power.

In New Jersey’s Hamilton Township, Tom Jacobsen also recalled heavy spring flooding and a particularly heavy winter before that.

“I’m starting to think we really ticked off Mother Nature somehow, because we’ve been getting spanked by her for about a year now,” he said.