Colorado Floods: Helicopters Rescue Stranded National Guard troops have used helicopters and military trucks to rescue residents stranded by floods that have claimed four lives in Colorado. The number of people unaccounted for has risen to 172 after the worst floods to hit the state for decades cut off towns and devastated communities over a 4,500 square mile (11,655 square km) area. Taking advantage of a break in torrential rains that have unleashed floodwaters up and down the state, Guard members rumbled into the hard-hit town of Lyons through waist-high water and went door to door to pull out up to 2,500 trapped residents. "These individuals are not only coming with just themselves, but with their suitcases and their precious household items along with their pets and everything, all getting loaded in the back of these vehicles," said First Lieutenant Skye Robinson, a spokesman for the Colorado National Guard. Deborah Haynes is led from a helicopter after being rescued from Jamestown Helicopters were evacuating 295 people - plus pets - from the mountain hamlet of Jamestown, which was isolated by flooding throughout the canyon the town sits in. Mike Smith, incident commander at Boulder Municipal Airport, said pilots would continue flying in and out late into the night, dropping food, water and other supplies to those awaiting an airlift. Rescue teams were also evacuating some stranded residents by boat, while some farmers managed to move to high ground on their tractors, Weld County sheriff's spokesman Steve Reams said in an interview with a local ABC television affiliate. A National Oceanic and Atmospheric Administration image of the storm system Thousands of evacuees have sought shelter in cities that were nearly surrounded by rivers bursting their banks. Governor John Hickenlooper said evacuations were the highest priority and advised people to stay out of debris and sand-filled floodwaters that were "almost like liquid cement." He told a news conference: "It's got to be the largest storm that I can imagine in the state's history." The flooding, so intense it toppled buildings in some places, began overnight on Wednesday. Boulder residents survey flood damage to the city's Topaz Street It was triggered by unusually heavy late-summer storms that drenched Colorado's biggest cities, from Fort Collins near the Wyoming border south through Boulder, Denver and Colorado Springs. Boulder and a string of other towns along the so-called Front Range of the Rockies north of Denver were especially hard-hit as water poured down rain-soaked mountains and spilled through canyons that funnelled the runoff into populated areas. Lyons, north of Boulder, was virtually cut off when floodwaters washed out US Route 36, and residents have been without water and power for 48 hours, said Mike Banuelos, a spokesman for the Boulder County Emergency Operations Center. At least four people were killed, including a couple swept away in floodwaters after stopping their car northwest of Boulder. Levin Sliker and Elizabeth Aisenbrey in their water-damaged living room The man's body was recovered on Thursday and the woman had been missing and feared dead before her body was found on Friday. Also killed were a person whose body was found in a collapsed building near Jamestown, an evacuated enclave north of Boulder, and a man in Colorado Springs, about 100 miles (160 km) to the south, officials said. The Boulder Office of Emergency Management listed 218 people as unaccounted for following the floods, stressing that while they were not yet considered missing or in danger, relatives and authorities had not been able to contact them. Authorities said many western mountain communities remained isolated with no potable water or working septic systems.