Emergency crews struggled with rushing water -- and still more rain -- Thursday night as they tried to reach people stranded by a flash flood blamed for at least three deaths along Colorado's Rocky Mountain range.
As Governor John Hickenlooper noted, Coloradans went to bed Wednesday night with no inkling that overnight rain could be heavy enough to flood canyons and send rivers of water from Boulder south to Colorado Springs.
Boulder County Sheriff Joe Pelle said the "devastating storm" dumped more than half a foot of rain on the region during a 19-hour period.
The widespread flash flooding washed out roads, pushed dams to their limits and beyond and killed at least three people.
And late Thursday President Barack Obama stepped in.
Obama signed an emergency declaration for Colorado, an action that helps allocate federal assistance to the issue.
There were dramatic rescues Thursday, including a man pulled from an overturned car in rushing water on live television. But for much of the day, rescuers had to wait at the edge of impassable roads or for skies to clear enough for helicopter flights.
Helicopters were still grounded as of 6 p.m. MT Thursday, said Ashlee Herring, a spokesperson for the city of Boulder.
The forecast was not encouraging. The National Weather Service issued a flash flood warning "until further notice" for Boulder Creek Thursday evening.
The worst of the reported damage has come in Boulder County, where the National Weather Service reported that a 20-foot wall of water roared down a mountain canyon north of the city.
One death was confirmed and another feared after a car stopped in the rushing water. Witnesses reported a woman emerged from the car and was swept away by the water. A man left the car and tried to reach her and also was overcome, Boulder County Sheriff's Cmdr. Heidi Prentup said. She said the man's body had been recovered, while the woman was missing.
Bodies also were found in a collapsed home in Jamestown and on a roadway in Colorado Springs.
Lyons, a small town of 2,000 near the foothills of the Rocky Mountains, was cut off by what city officials described as a 500-year flood.
People were using the city's Facebook page to search for loved ones, hunt for medicine and even ask for pet food. One post described people riding to safety on a backhoe.
National Guard rescuers in high-water vehicles reached Lyons with humanitarian aid Thursday night, Prentup said, but the town remained otherwise cut off.
City officials used Facebook to appeal to residents to take in people and pets who were sheltering at an elementary school because they feared the school would lose power Thursday night.
One Lyons resident said it was "almost amusing" to see news video of "debris here and there" in other cities. "They haven't seen this stuff here yet," she wrote. Photos on the Facebook page showed swirling water halfway up street signs and a washed-out bridge.
Elsewhere, homes collapsed onto residents and a dam in Larimer County broke, flooding some homes and leaving three people trapped, a county spokesman said.
Larimer County Sheriff Justin Smith said some residents there face the dilemma of whether to try to move to safer shelters over bridges that may have been damaged. They will "have to use their own judgment," he said.
An emergency message from the sheriff's office to residents of Big Thompson Canyon said, "If you are cut off because of a compromised bridge, you need to stay at your residence but have a plan to get to higher ground at a moment's notice."
Pelle said emergency crews were worried about a Lyons Fire Department crew stuck on a mountainside near a washed-out road. Hypothermia from the cold, wet conditions was of particular concern, he said.
As of Thursday evening, authorities in Boulder had not been able to make contact with the Lyons Fire Department to confirm that the firefighters had been rescued, Herring said.
As dawn broke over the region, Pelle said he was "amassing a large-scale effort" to rescue those who are trapped, reach those who are stranded and deliver much needed aid to places like Lyons, where floodwater overtopped several dams protecting the town.
Hickenlooper said later in the day that two National Guard Black Hawk helicopter search-and-rescue crews were sent to Boulder County, along with three swiftwater rescue teams and emergency managers. One helicopter and emergency managers were dispatched to Larimer County.