Rescue teams responding to the Colorado floods have warned residents to evacuate their homes or face being stranded for weeks without electricity, water or basic supplies.
Amid apocalyptic scenes across the foothills of the Rocky Mountains, at least four people have died and hundreds remain unaccounted for.
Some areas have seen more than 15 inches (38.1cm) of rainfall in three days – above the average expected for a whole year – in what a county commissioner has called a “500- to 1,000-year flood”.
State authorities say that with more rain forecast for the next two days, further fatalities are all but inevitable. The death toll is expected to rise to five shortly, with a 60-year-old woman missing and feared dead after neighbours witnessed her mountain home being swept away.
President Barack Obama has now signed a disaster declaration, and ordered federal aid to be sent to Colorado.
As of Saturday night, 1,750 people and 300 pets had been evacuated from the Boulder and Larimer County regions, with the military adding more troops and helicopters to the ongoing search and rescue effort.
With thousands more people stranded in rural canyon towns, and rescue teams impeded by waters washing away the state’s transport infrastructure, the authorities have issued a stern warning to anyone thinking about trying to stay in their homes and weather the storm.
Boulder County Sheriff Joe Pelle said anyone refusing evacuation assistance must brace themselves to be cut off for weeks, without power, running water or the delivery of supplies.
Rescuers would not be coming back for some time to pick up anyone who insisted on staying, he said.
“We're not trying to force anyone from their home. We're not trying to be forceful, but we're trying to be very factual and definitive about the consequences of their decision, and we hope that they will come down,” Sheriff Pelle said.
Special education teacher Brian Shultz, 38, was torn about leaving his Jamestown home.
“I was thinking about staying. I could have lasted at least a year. I have a lot of training in wilderness survival,” he said, adding that he probably had enough beer to last the whole time.
The Boulder Mountain Fire Protection District sent out a message warning trapped residents that rescuers were having difficulty reaching them.
“We continue to have new landslides and road collapses,” the statement said.
With nearly 250 people listed as missing, Sheriff Pelle said that “given the destruction, there is a high probability” of more fatalities.
Touring the affected region by helicopter alongside Governor John Hickenlooper – and stopping to pick up seven evacuees and two pets on the way – US Senator Mark Udall said: “This event has stunned all of us.”
It is the worst flooding to hit the state since 1976, when nearly 150 people died in Larimer County in a flash flood along the Big Thompson Canyon.