Rescuers broke through to flood-ravaged Colorado towns where thousands of stranded residents were eager to escape, warning stragglers that they must be prepared to endure weeks without electricity, running water and basic supplies.
Helicopters and truck convoys carried the message to Rocky Mountain foothill communities paralysed by days of rain that unleashed harrowing floods. Four people have been confirmed dead since floods began on Wednesday and hundreds of others in the flood zone have not been heard from.
Not everybody was willing to evacuate. Dozens of people in the isolated community of Jamestown wanted to stay to watch over their homes.
Authorities made clear that residents who chose not to leave might not get another chance for a while. Rescuers won't go back for people who insist on staying, Boulder County Sheriff Joe Pelle 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," he 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 as he sat outside a makeshift shelter at a high school.
Across the foothills, rescuers made progress against the floodwaters. But they were still unable to go up many narrow canyon roads that were either underwater or washed out.
On Saturday the surge of water reached the plains east of the mountains, cutting off more communities and diverting some rescue operations.
Some of those who were unaccounted for may be stranded or injured. Others might have gotten out but not yet contacted friends and relatives, officials said. Police expected to find more bodies as the full scope of damage emerges. 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.
President Barack Obama has signed a disaster declaration and ordered federal aid for Colorado.