MONTPELIER, Vt. — The remnants of Hurricane Irene dumped torrential rains on Vermont on Sunday, flooding rivers and closing roads from Massachusetts to the Canadian border, putting parts of two towns under water and leaving one young woman swept away and feared drowned in the Deerfield River.

Parts of downtown Brattleboro and Bennington were under water, as were several smaller communities. State and local authorities warned people to stay off the roads, and Montpelier officials ordered downtown residents to be ready to evacuate Sunday evening.

“This is the worst I’ve ever seen in Vermont,” said Mike O’Neil, director of Vermont Emergency Management. “It’s so widespread. Usually we deal with more localized situations, but this is spread throughout the state.”

The storm began with rain early in the day, heaviest in the southern part of the state, moving slowly north as the day went on. By late afternoon, officials were reporting scores of road closures from flooding from Guilford on the Massachusetts line to Derby, which borders Quebec. The high waters at one point shut down a short stretch of Interstate 91. Many people were forced to leave their homes.

“It’s pretty fierce. I’ve never seen anything like it,” said Michelle Guevin, who spoke from a Brattleboro restaurant after being evacuated from her home in nearby Newfane. She said her house was high enough to be OK, but the fast-moving Rock River was washing out the road that went by it.

By 6 p.m., much of the state had picked up 4-6 inches of rain, with 1 to 2 more inches forecast before it was expected to taper off as the storm exited northern Vermont.

“It’s really important that Vermonters take this storm seriously and stay inside,” Gov. Peter Shumlin said at an afternoon news conference at Vermont Emergency Management headquarters.

Shumlin said a woman, whose name was not released, was reported missing after she was swept away in the swollen Deerfield River in Wilmington after falling in while watching the river with a friend Sunday morning.

The center of Wilmington, a ski resort town at the junction of Vermont Routes 100 and 9, was flooded by the East Branch of the Deerfield River but could not be reached by either of those state roads due to washouts. Vermont National Guard members deployed in a rescue operation had to travel south of the state line and travel back north from Massachusetts, Shumlin said.

Across the state, there were reports of culverts and roads being washed away, large trees coming down and water entering people’s homes. Rescue workers were dispatched to a stream in Grafton, where a woman was reported clinging to a tree in rushing water.

The storm’s path shifted west of what was initially forecast, moving up through western Vermont and eastern New York state rather than the Connecticut River valley.

Shumlin cautioned that Vermonters should stay at home even after the storm appears to have passed. Roads will be flooded and power lines down, creating continuing dangers, he said. He urged Vermonters to not stand next to rushing water and to “proceed with extraordinary caution and good judgment.”

The storm did not produce winds as strong as had been feared, with gusts topping 50 mph but not getting to the 70 mph forecasters had predicted. Even the lesser winds were enough to topple trees onto power lines, and by mid-afternoon more than 25,000 electric customers without power, utility officials said.

“Line crews have been restoring outages since early this morning, but in some areas extreme flooding conditions and road closures are hampering our ability to respond and restore power, especially in Dover and Wilmington,” said Dottie Schnure, spokeswoman for Green Mountain Power Corp.

The state ordered all nonessential employees to delay their start Monday until 10 a.m., and to check their email Monday morning for notifications of possible further delays. The University of Vermont in Burlington delayed the start of fall classes, which had been set for Monday, until Tuesday.

7:19 p.m.: Torrential rains soak Vermont

MONTPELIER, Vt. — The remnants of Hurricane Irene have dumped torrential rains on Vermont, leaving parts of several towns underwater, closing roads across the state and leaving one woman feared dead.

Mike O’Neil, director of Vermont Emergency Management, described Sunday’s flooding as “the worst I’ve ever seen.” He said flooding is occurring across the entire state, from the Canadian border to the Massachusetts border.

Parts of downtown Brattleboro and Bennington were underwater, and that was true in several smaller communities. Montpelier officials ordered downtown residents to be ready to evacuate this evening.

This morning, a young woman was reported swept away and feared drowned in the swollen Deerfield River in Wilmington. Rescue workers were also dispatched to a stream in Grafton, where a woman was reported clinging to a tree in rushing water.