LYONS, Colo. >> By truck and helicopter, thousands of people stranded by floodwaters came down from the Colorado Rockies today, two days after seemingly endless rain turned normally scenic rivers and creeks into coffee-colored rapids that wrecked scores of roads and wiped out neighborhoods.

Authorities aimed to evacuate 2,500 people from the isolated mountain community of Lyons by the end of the day, either by National Guard convoys or airlifts.

One of them, Mary Hemme, recalled hearing sirens going off in the middle of the night and her husband saying they needed to leave. They stepped outside their trailer and into rushing water that nearly reached their knees.

She got in her car and tried to drive away.

"But I only got so far, because the river was rushing at me, so I threw it in reverse as fast as I could," Hemme said. "I was so afraid that I was going to die, that water came so fast."

Others were less fortunate. The body of a woman who had been swept away was found Friday near Boulder, raising the death toll to four.

National Guard troops aided by a break in the weather started airlifting 295 residents from the small community of Jamestown, which has been cut off and without power or water for more than a day.

Dean Hollenbaugh, 79, decided to take one of the helicopters after officials warned electricity and water could be disrupted for weeks.

"Essentially, what they were threatening us with is ‘if you stay here, you may be here for a month,’" Hollenbaugh said as he waited for his son to pick him up from the Boulder airport. "I felt I was OK. I mean I’ve camped in the mountains for a week at a time."

Airlifts also were taking place to the east in Larimer County for people with special medical needs.

The relentless rush of water from higher ground turned towns into muddy swamps, and the rain returned Friday afternoon after a brief lull. In at least one community, pressure from the descending water caused sewer grates to erupt into huge black geysers.

Damage assessments were on hold, with many roads impassable and the rain expected to continue.

"This one’s going to bring us to our knees," said Tom Simmons, president and co-owner of Crating Technologies, a Longmont packing service that had its warehouse inundated. "It’s hoping against hope. We’re out of business for a long time."

Most of the 90 miles of Interstate 25 from Denver to Cheyenne, Wyo., was closed Friday because of flooding from the St. Vrain, Poudre and Big Thompson rivers, transportation officials said.

Hundreds of people were forced to seek emergency shelter up and down Colorado’s heavily populated Front Range, which has received more than 15 inches of rain this week, according to the National Weather Service.

That’s about half the amount of precipitation that normally falls in the foothills near Boulder during an entire year.

Boulder County officials said 80 people were unaccounted for Friday. But, they noted, that doesn’t necessarily mean they’re missing.

"It means we haven’t heard back from them," county spokesman James Burrus said.

Two backpackers became stranded on Longs Peak, one of Colorado’s highest mountains, after the weather turned. Suzanne Turell and Connie Yang of York, Maine, last sent a text message Thursday with their GPS coordinates, but their cellphones went dead, said Turell’s mother, Barbara.

The pair hiked off the mountain themselves as the National Park Service was organizing a rescue effort.

The park service closed Rocky Mountain National Park and was escorting visitors and residents of Estes Park on a trail over the Continental Divide.

In Lyons, residents took shelter on higher ground, including some at an elementary school, before convoys could push through the water and into the isolated town. The convoys carried 15 people at a time to buses beyond the roadblocks, past cheering crowds.

Dawn Lundell and John Johnson decided not to wait, instead hiking from the town through 200 yards of water in a canal. They described a "calm, reasonably festive" atmosphere among those who remained.

"Nobody minds roughing it a little bit in Lyons. We’re all outdoorsy people. We call it Mayberry. Everybody helps each other and everybody loves each other, so we’re all helping each other out," Lundell said.

The Big Thompson Canyon, scene of the deadliest flash flood in state history in 1976, was devastated by the latest flooding.

Numerous homes have been destroyed there and the roadway has been swept away in many locations, Larimer County Sheriff Justin Smith said.

Between the Big Thompson and Little Thompson rivers, Jose Ayala spent Friday morning picking through what was left of his family’s possessions in their two-story farmhouse near Berthoud.

He and his sons watched the waters rise all Thursday evening, finally making the decision to flee at 11 p.m. with some documents and a computer.

"The rest is in the house. All gone, basically," Ayala said.

Some of the flooding was exacerbated by wildfire "burn scars" that have spawned flash floods all summer in the mountains. The flames strip away vegetation that normally helps absorbs excess water and leave a residue that sheds water.

One person was killed when a structure in Jamestown collapsed. Another man drowned in floodwaters north of Boulder while trying to help the woman whose body was found Friday.

To the south, Colorado Springs officers conducting flood patrols found the body of a 54-year-man in a creek.

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Contributing to this report were Associated Press writers Colleen Slevin, Steven K. Paulson and Thomas Peipert in Denver; and Ben Neary in Longmont.