NEW YORK – A powerful nor’easter pounded the East with wind and pouring rain Sunday, grounding airlines and threatening to create some of the worst coastal flooding in 14 years.

One person was killed as dozens of mobile homes were destroyed or damaged by wind in South Carolina. The storm system already had been blamed for five deaths on Friday in Kansas and Texas.

As snow and rain swept across Maine on Sunday night, Gov. John Baldacci signed an emergency declaration. “We’re concerned about heavy snow, high winds and intense rain. State and local emergency management personnel on are duty, and we are preparing for what could be a significant event,” Baldacci said in a statement.

Forecasters said the heaviest precipitation would fall during the night and into today, the Patriot’s Day holiday in Maine.

Emergency officials were worried about the potential for widespread power outages caused by tree limbs falling onto electric lines because of heavy snow and high winds. Weather forecasters said gusts of 55 mph were expected Sunday night.

The emergency declaration going into effect at midnight would speed repairs by allowing crews from other areas to travel to Maine, said David Farmer, the governor’s spokesman. The Maine Emergency Management Agency was staffed through the night.

The National Weather Service posted a winter storm warning through today over higher elevations in Maine, New Hampshire and eastern Vermont, with forecasts calling for near-blizzard conditions and up to 18 inches of snow.

A winter weather advisory was in effect in many other areas, along with a high wind warning and a coastal flood warning.

The storm was expected to stall over New York City for 24 hours starting this morning before moving out on Tuesday. “But it will still be affecting our weather here through Wednesday,” Hawley said.

Predictions of 3 to 5 inches of rain on and near the coast fueled concerns about coastal flooding and overflows from small rivers and streams.

A couple dozen arriving and departing flights were canceled at Manchester-Boston Regional Airport and Portland International Jetport, mostly because of bad weather at other locations.

Airlines canceled more than 350 flights at the New York area’s three major airports, said Steve Coleman, a spokesman for the Port Authority of New York and New Jersey. More cancellations were expected throughout the day.

Flight delays at Logan Airport in Boston averaged in excess of two hours, according to airport spokeswoman Lisa Langone, and more than 70 flights were canceled as of 4:30 p.m.

Heavy rain and thunderstorms extended from Florida up the coast to New England on Sunday. Wind gusted to 71 mph at Charleston, S.C., the weather service said.

Storm warnings and watches were posted all along the East Coast, with flood warnings extending from North Carolina to the New York area. Winter storm warnings were in effect for parts of New England and eastern New York state.

Meteorologists expected sustained wind of 40 mph and a storm surge of 3 to 5 feet, a combination that could cause as much coastal damage to New York’s Long Island as a winter storm that wreaked havoc there in late 1992, Gov. Eliot Spitzer said.

Ferry service to Fire Island, off the south shore of Long Island, was halted, and New York City opened nine emergency storm shelters in flood-prone locations. Spitzer sent 3,200 National Guard members to potential flood areas.

Some residents of low-lying areas along the New Jersey shore packed up to leave.

“This is going to be bad,” Shaun Rheinheimer said as he moved furniture to higher spots at his house on New Jersey’s Cedar Bonnet Island. Streets were flooded and waves splashed over bulkheads into backyards.

The storm also caused flash flooding in the mountains of southern West Virginia, where emergency services personnel rescued nearly two dozen people from homes and cars in Logan and Boone counties early Sunday. Two people were unaccounted for.

“It’s about as bad as it can get,” said Logan, W.Va., Fire Chief Scott Beckett. “This thing came down at 2 or 3 in the morning, when people were sleeping in their beds. They just didn’t know what was happening.”

Some remained trapped in their homes because roads were blocked by high water or mud, said Dean Meadows, Wyoming County emergency services director.

Up to 2.5 inches of rain had fallen in southern West Virginia since early Saturday and streams were still rising Sunday, said weather service meteorologist Dan Bartholf in Charleston.

At least 3 inches of rain fell in eastern Kentucky, where a 50-foot section of highway collapsed near Pikeville, said state police Sgt. Jamey Kidd. No vehicles were caught by the collapse, he said.

Dozens of homes were destroyed or blown off their foundations in several areas of South Carolina’s Sumter County, but authorities didn’t immediately know whether the cause was a tornado or straight-line wind, said county emergency management director Robert Baker Jr. One person was killed and four were seriously injured, he said.

In central Florida, a tornado damaged mobile homes in Dundee but no injuries were reported, police said.

Associated Press writers Wayne Parry in Manahawkin, N.J., Daniela Flores in Trenton, N.J., and Tom Breen in Madison, W.Va., also contributed to this report.