Torrential rains continued to fall Thursday in northern Colorado, where rescuers are struggling to reach dozens of people cut off by flooding in mountain communities. Three deaths have already been confirmed.
At least two people died in flooding in Boulder County. The body of one was found in a collapsed building by emergency crews searching door to door for victims in and around Jamestown. The other drowned elsewhere in the county, Cmdr. Heidi Prentup of the Boulder County Sheriff's Office said.
The body of a third victim, a man, was found by police on flood-watch patrols in Colorado Springs, about 100 miles to the south, officials said.
County Sheriff Joe Pelle said it was possible that more flood-related fatalities could emerge as emergency crews reached areas cut off by high water.
Downpours and scarring from recent wildfires sent walls of water crashing down mountainsides Thursday, forcing thousands to evacuate as rising water toppled buildings and stranded motorists in their cars, officials said.
The towns of Lyons, Jamestown and others in the Rocky Mountain foothills have been isolated by flooding. Residents have no power or telephone service.
Boulder County was hardest hit, with authorities instructing residents to stay off roads.
The Boulder Office of Emergency Management told residents to seek higher ground, boil their drinking water in some areas, and stay away from the water that it called "hazardous" because of its speed and possible contamination with sewage.
"There is water everywhere," said Andrew Barth, the emergency management spokesman in Boulder County. "We've had several structural collapses. There's mud and muck and debris everywhere. Cars are stranded all over the place."
Al Jazeera's Tamara Banks, reporting from Colorado, said at least 2,000 people were ordered evacuated from Commerce City, a northern suburb of Denver.
At least 6 inches of rain had fallen on the city of Boulder, northwest of Denver, and up to 8 inches were measured in the foothills west of the city, said Kari Bowen, a Weather Service meteorologist in Boulder.
Heavy rains drenched Colorado's biggest urban areas, stretching 130 miles along the eastern slopes of the Rockies from Fort Collins near the Wyoming border south through Boulder, Denver and Colorado Springs.
Ron Cobbley, 49, a homeless man who had been camping along the St. Vrain River west of Boulder near the town of Ward, said he decided to leave the woods and head into town after three days in the rain.
"It was raging with whitewater," he said of the river.
Steady rain that began on Monday grew more intense late Tuesday and into Wednesday. Roads across the region were flooded out, and standing water throughout Denver snarled the morning rush hour in the state capital.
Barth, the Boulder County emergency management spokesman, said conditions were "extremely dangerous" and that up to 4 inches of additional rain was expected to fall before tapering off.
All 200 residents of Jamestown, just north of Boulder, were forced to flee overnight, while the town of Lyons, farther to the north, was cut off as floodwaters washed out U.S. Route 36 linking Lyons to Boulder, Pelle said.
He said Lyons had reported that its residents had no fresh running water and its sewage treatment plant had been knocked out.
"We're trying desperately to get to them," Pelle said.
Al Jazeera and wire services