LYONS, COLO. (CBS NEWS) - The rescue of Coloradoans stranded by epic mountain flooding accelerated Saturday as debris-filled rivers became muddy seas that extended into towns and farms miles from the Rockies. Authorities expected to find more fatalities when full scope of destruction emerged.
Helicopters and hundreds of National Guard troops searched the mountainous terrain for people as food and water supplies ran low in remote communities cut off since Thursday. Thousands were being driven to safety in convoys.
People were not the only ones trapped, reporter Rick Sallinger of CBS Denver station KCNC-TV reported from Boulder on "CBS This Morning: Saturday." Herds of cows and other animals were seen standing in deepening waters. One man rode his horse to safety.
A woman was missing and presumed dead after witnesses saw floodwaters from the Big Thompson River destroy her home in the Cedar Cove area, Larimer County sheriff's spokesman John Schulz said.
"We're sure there are going to be additional homes that have been destroyed, but we won't know that for a while," Schulz said. I expect that we're going to continue to receive reports of confirmed missing and confirmed fatalities throughout the next several days."
Four people have been confirmed dead since the harrowing floods began Wednesday. The high water has affected an area nearly the size of Connecticut.
National Guard helicopters flew in and out of the mountain hamlet of Jamestown late into Friday night after it became isolated by rushing water that scoured the canyon the village sits in. Rescuers on the ground focused on the town of Lyons.
By Saturday morning, the Guard had evacuated nearly 800 people by air and ground.
More than a dozen helicopters were available to aid with rescue efforts.
"We have the ability to go whenever, wherever," Master Sgt. Cheresa Theiral said.
Still more rain was expected Saturday. And the outlook for anyone who preferred to stay behind was bleak: weeks without power, cellphone service or running water.
"Essentially, what they were threatening us with is, 'If you stay here, you may be here for a month,'" said 79-year-old Dean Hollenbaugh, who was evacuated by helicopter from Jamestown, northwest of Boulder.
For those awaiting an airlift, Guardsmen dropped food, water and other supplies to residents of the winding, narrow canyons that cut through the Rocky Mountain foothills.
Although the number of confirmed deaths stood at four, authorities feared more bodies could turn up in areas that remain inaccessible.
"The thing with this event is, we don't know what we don't know," Boulder County Sheriff Joe Pelle said.
More than 170 people remained unaccounted for in Boulder County, but that number could include people who are still stranded or who escaped but have not made contact yet, the sheriff said.
One was Mary Hemme, 62, who displayed a pair of purple socks as she sat outside the Lifebridge Christian Church in Longmont. The socks were a memento of the more than 30 hours she spent in an elementary school in Lyons. Many evacuees were given dry socks because most had wet feet, Hemme said.
She recalled the sirens blared at 2:30 a.m. Wednesday.
"Mary, we have to go. This place is flooding," she recalled friend Kristen Vincent saying as they clambered out of a trailer into water that was nearly knee-deep.
"It wasn't just sitting there," she said. "It was rushing at us."
Soon the trailer, like others in the park where she was staying, was submerged.
Hemme said she walked up at hill a daybreak and surveyed the trailer park.
"The most terrifying thing was when I climbed up on that cliff and looked down," she said. The water had carried cars as if they were toys.
"I was so afraid that I was going to die, that water came so fast."
The dayslong rush of water from higher ground turned towns on Colorado's expansive eastern plains into muddy swamps. Crews used inflatable boats to rescue families and pets from stranded farmhouses. Some evacuees on horseback had to be escorted to safe ground.
The city of Boulder reported late Friday that the rushing waters had caused "a significant breach in its main wastewater pipeline" to the treatment plant, but officials said it would not affect drinking water.
Near Greeley, some 35 miles east of the foothills, broad swaths of farmland had become lakes, and the raging South Platte and Poudre rivers led to rescues of stranded residents late into the night, the Greeley Tribune reported.
Hundreds of roads were closed or damaged by floodwaters, and a 70-mile stretch of Interstate 25 was closed from Denver to the Wyoming line.
Rocky Mountain National Park closed Friday, its visitors forced to leave via the 60-mile Trail Ridge Road to the west side of the Rockies.
It will be weeks, if not months, before a semblance of normalcy returns to Lyons, a gateway community to the park. The town, surrounded by sandstone cliffs whose color was reflected in the raging St. Vrain River, consisted of six islands Friday as residents barbecued their food before it spoiled. Several people set up a tent camp on a hill.
Some 2,500 residents were being evacuated from Lyons, but Hilary Clark was left walking around her neighborhood Friday.
Two bridges that led into the area were washed away. Unlike other parts of Lyons that had been reached by the National Guard in high clearance trucks, no such help had arrived for Clark.
"We're surviving on what we got," she said. "Some of us have ponds in our backyard, and we're using that water and boiling it."
Boulder County Sheriff Joe Pelle said recovery would be long and expensive — similar to wildfires the state is more familiar with.
"Please be patient," he said. "This is an unprecedented event."