Colorado Towns Are Left Stranded in Deadly Floods Rick Wilking/Reuters Flash floods in Colorado killed at least three people on Thursday. A home and car were stranded after flooding in Coal Creek. BOULDER, Colo. - Walls of water cascading down hillsides caused flash floods across Colorado on Thursday, killing at least three people. The flooding cut off major highways, isolated mountain towns and closed the main campus of the University of Colorado, the authorities said. "This is not your ordinary disaster," said Joe Pelle, the sheriff of Boulder County, where two of the deaths were reported, when he was asked about rescue efforts. All the preparation in the world, all the want-to in the world, can't put people up those canyons while debris and walls of water are coming down. As heavy rain continued falling late Thursday, homes, bridges and small dams built along the mountains that bisect the state collapsed, succumbing to rushing floodwaters and record levels of rainfall. Mudslides swept down hillsides left treeless by recent wildfires. Firefighters made dozens of rescues as cars were overtaken by rain-swollen creeks and roads suddenly gave way. One volunteer fire crew was stranded on a mountainside after a wave of rainwater abruptly washed out a road, the authorities said. Much of the worst of the flooding Thursday appeared to be in Boulder, where the university canceled classes Thursday and Friday and some 500 students and staff members were ordered evacuated. Dozens of buildings have been damaged, the university said, including the school's theater and the Norlin Library. A message posted on the university's Web site Thursday announced: "Wall of water coming down Boulder Canyon. But the warning did not dissuade some people from flocking there. They stood on bridges marveling at the torrent of fast-moving brown water as it swept away anything in its path. "I've never seen anything like this," said Ryan Corbett, 24, a student who was among the onlookers. I've lived here for seven years. This is unreal. A few miles north, a 50-yard wide portion of Route 36 was submerged as a stream bed overflowed and coursed by at 1,000 cubic feet per second, said Anne Reid, a firefighter with the Lefthand Fire Protection District. "This is usually just a little stream that you wouldn't even think to fish in," Ms. Reid said. The flooded highway has cut off residential areas for the foreseeable future, sweeping up whole willow and cottonwood trees as if they were twigs. John and Billie Brumder, who live across from the Crestview Estates neighborhood, said they were awakened at about 1:30 a.m. Thursday by the frightening sound of large rocks being dragged along the creek bed. "When I heard that, I knew it was a big deal," he said. I knew we had to get out of there. Their car, which was already partly submerged, stalled, Mr. Brumder said, but they were able to escape in their pickup truck. The authorities said Thursday afternoon that they expected the death toll in the state, currently at three, to rise. One person drowned and a second person was killed when a structure collapsed in the town of Jamestown, northwest of Boulder. The third victim was found in Colorado Springs by police officers conducting flood patrols. Rain had been falling in the Boulder area since Monday, but picked up significantly on Wednesday evening, causing mudslides in Colorado's Front Range, where since 2010 wildfires have denuded some areas of trees and brush that would have normally helped soak up the moisture. Dozens of streams and creeks overflowed, and downstream, portions of Colorado Springs and Denver flooded, as well as large parts of Boulder. The National Weather Service reported that more than 6 inches of rain had fallen in a 12-hour period. Forecasters predicted that the rain would continue into Friday. According to provisional data from the United States Geological Survey, parts of Boulder Creek reached flood levels that have a 1 in 100 chance of occurring in any given year - what some refer to as a 100-year flood. Sylvia Tawse, who owns a vegetable and flower farm in Longmont, said her husband got a call at 3 a.m. from the local fire chief, warning that a 20-foot wall of water was barreling down nearby Left Hand Creek. Ms. Tawse's property, nestled among a patchwork of family farms about 10 miles north of Boulder, was spared. But her neighbors were not so lucky. "We're on slightly higher ground, so we're not in danger," she said. But their farm fields are completely underwater. Ms. Tawse said that by early Thursday, Left Hand Creek, typically barely a trickle, had swollen into a raging rush of muddy water. "We had a bad flood here in 1995," she said. But this is worse than that. Dan Frosch reported from Boulder, and Timothy Williams from New York.