EPSOM, N.H. - A violent thunderstorm with tornado-like winds tore through New Hampshire yesterday, killing one person in a collapsed house and causing heavy damage in its 21-mile path through 11 small towns in the center of the state.

The storm set down just before noon and cut a swath of damage from Epsom to New Durham.

In Deerfield, about 12 miles east of Concord, a woman died when the house she was in collapsed. Brenda J. Stevens, 57, was at 104 Sleepy Hollow Lane with her husband and a 3-month-old baby when she was killed.

Emergency officials said about 12 people were hurt.

The powerful, fast-moving storm, which meteorologists suspect was a tornado, leveled a dozen houses and damaged about 100 more, trapping some families within, emergency officials said. In the hardest-hit areas, police and firefighters went house to house searching for victims.

With winds estimated at up to 100 miles per hour, the storm battered buildings, snapped trees, and downed power lines, leaving about 5,000 homes and businesses in about 11 communities without electricity.

Some residents could be without power and water for several days.

The unusually severe weather, which battered a narrow area east and northeast of Concord with torrential rains and widespread lightning, caused flooding, littered the ground with debris, and left many roads impassable, displacing residents from their homes and delaying emergency responders.

"We're at sixes and sevens here," said Carol Locke, an assessing clerk who was answering phones at Town Hall in Barnstead, which was among the hardest-hit towns. "There's power lines down, houses have collapsed, and mobile homes tipped over."

Governor John Lynch declared an emergency in five counties and called in the National Guard to help in the recovery.

"This was a highly destructive storm, causing a tremendous amount of damage in a short period of time," he said at an evening press conference at emergency management headquarters in Concord.

More than 100 state and federal agencies were involved in the response in New Hampshire. Authorities are monitoring potential flooding of the Connecticut River, the Pemigewasset River in Woodstock, and the Saco River.

The Federal Emergency Management Agency plans to assess the damage this morning. In Epsom, winds blew a house 75 feet from its foundation.

"This is just a straight line of damage," State Police Colonel Frederick Booth said, estimating that 100 houses were damaged. "When it's all said and done, it'll probably be more than that."

Michael Cempa, a National Weather Service meteorologist, said it appears that a tornado had struck the area. "Everything we see suggests it was a tornado," he said.

Cempa said a National Weather Service group will also investigate reports of a second possible tornado in the Wolfeboro area.

The rain was expected to subside overnight with the possibility of scattered showers this morning. The afternoon was expected to be dry.

Tornadoes are rare but not unprecedented in the region, with one or two touching down in New Hampshire and Maine every year, meteorologists said.

The National Weather Service confirmed yesterday that a small tornado set down in Rhode Island and traveled about 4 miles into Massachusetts Wednesday, damaging houses and knocking down trees and power lines. No injuries were reported.

"I knew within the first five minutes of receiving calls it was a very serious incident," said Christopher M. Pope, New Hampshire's director of emergency management and homeland security.

In Epsom, Karen Dail was in her barn shoeing her horse when the storm came.

"My husband is from Texas and always says, 'If the sky turns green, there's a tornado coming,' " she said. "When we looked out, it was getting green, and you could see a funnel.

"You could see the clouds twisting on the road," Dail said. ". . . Kayaks were hanging like kites in the woods."

In Barnstead, Craig Obrenovich, 18, rushed his 11-year-old sister and 9-year-old brother into the basement as soon as he heard the roar of the storm.

"All I could see was rain, and it was dark, and then it started whistling," he said. Five minutes later, he emerged to a chaotic, debris-strewn landscape.

Emergency crews worked to clear roads blocked by downed trees and power lines.

"We're cutting hand paths so we can go down on the highways," said Shawn Mulcahy, deputy fire chief in Barnstead.

"Many of our smaller roads are blocked with huge trees, power lines, broken poles, and debris taller than a person," Mulcahy said.

Mulcahy said some residents would not have power or water for days.

The town had created an emergency center and shelter for people displaced from their homes.

The 11 New Hampshire communities affected were Deerfield, Epsom, Freedom, Ossipee, Wolfeboro, Alton, New Durham, Barnstead, Northwood, Candia, and Deering.

In Epsom, Bob Blodgett, chairman of the Board of Selectmen, said the close-knit town was a scene of devastation.

"You couldn't believe only one person lost their life," he said from an elementary school that is serving as a temporary shelter. "It looked like somebody had a 200-foot mowing machine that cut the trees right off."

After watching the storm coverage on television, Maye Hart rushed back to her Epsom neighborhood. "I can see the roof, and it's still there, but about three doors down, it looks like the house collapsed," she said.

In Barnstead, Shawn and Melissa Williams could not make it to their home to see the damage. A neighbor told them that several trees were down in the yard and that about four trees had crashed into the neighbor's house.

"It's a real tragedy. All you have to do is look around," said Deputy Fire Chief Rodney Boyd.

In Massachusetts yesterday, 2 to 3 inches of rain fell, and hail and strong winds hit Springfield and Holyoke, according to National Weather Service reports.

In Saugus, eight to 10 houses on Hesper Street were evacuated at 7:30 last night because "a large retaining wall on Hitching Hill Road had started to collapse," said police Lieutenant David Putnam.

No one was injured, and no houses were damaged as of last night, he said.