Rivers and creeks continued to rise to dangerous levels in Boulder County and neighboring parts of Colorado as the death toll rose to four Friday, with 172 people unaccounted for. President Barack Obama has signed an emergency declaration, freeing federal aid and allowing the Federal Emergency Management Agency to coordinate disaster-relief efforts.
Some of the flooding was exacerbated by wildfire burn scars that spawned flash floods all summer in the mountains. That was particularly true in an area scarred by fire in 2010 near the tiny community of Jamestown and another near Colorado Springs' Waldo Canyon that was hit in 2012.
In Boulder and the village of Eldorado Springs, rescuers struggled to reach dozens of people cut off by flooding in mountain communities. Residents in the Denver area and other downstream communities were warned to stay off flooded streets.
The towns of Lyons, Jamestown and others in the Rocky Mountain foothills have been isolated by flooding and have been without power or telephone service since rain, hanging over the region all week, intensified late Wednesday and early Thursday.
At least four people have died in the floods, with authorities indicating that a fifth fatality was likely. Many people were forced to seek shelter up and down Colorado's populated Front Range.
The University of Colorado canceled classes at least through Saturday after a quarter of its buildings were flooded. Students in family housing who were originally evacuated were allowed to return late Friday, but were asked to remain on alert for future evacuation notices.
On Long Peak, about 40 miles from Boulder County, two hikers stranded for 48-hours walked to safety Friday, The Denver Post reported. Connie Yang and Suzanne Turell had sent text messages from the mountain saying they were pinned down by an ice storm and not equipped for the cold weather.
Al Jazeera and The Associated Press