Rescue crews in Colorado, mounting what was called the largest civilian helicopter mission since Hurricane Katrina, waited for clear weather Monday in hopes of reaching hundreds of people trapped by catastrophic floods.
Authorities were preparing to dispatch helicopters to rescue an unknown number of people stranded in Jamestown, a northwest Boulder County town of fewer than 300 residents that was left virtually unreachable after floodwaters swallowed huge swaths of the primary access road, said Nick Grossman, a spokesman for the county's office of emergency management.
Jamestown is "essentially an island right now," Grossman said, adding that some 45 people have already been evacuated from the flood-ravaged town.
Officials instructed isolated people in other hard-hit mountain towns to set flares, wave light-colored sheets from the roofs of houses and use mirrors to reflect the sunlight and attract the attention of the teams sent to save them.
At a press briefing Monday, Gov. John Hickenlooper said saving lives was the state's top priority, adding that some 21 helicopters were conducting search and rescue operations while FEMA officials scrambled to assist flood-hit families and individuals.
The floods, which Sen. Mark Udall on Monday described as "liquid tornados," have killed at least five people, wrecked more than 17,000 homes and left more than 1,200 people unaccounted for. Phone service, cell and landline, was out across much of the disaster zone, blocking authorities from knowing the full human toll.
"I'm hopeful that the vast majority of these people are safe and sound," Hickenlooper said on NBC's TODAY. "But we do not have any illusions that there could well be more casualties."
In Larimer County, along the Wyoming state line, 16 helicopters from the National Guard and other agencies stood by. According to the county sheriff's office's Twitter account, the weather was expected to break around 10 a.m. local time (1 p.m. ET), with aerial rescues to follow shortly after.
In Boulder County, closer to Denver, crews were going house to house looking for stranded people. The Army and National Guard had rescued at least 1,750 people cut off by washed-out roads in the mountain canyons, an Army spokesman said.
Search-and-rescue teams from Utah, Nebraska, Nevada, California and Missouri were in Colorado or on their way to help, according to KUSA, the NBC affiliate in Denver. The floods have wrecked
Forecasters said the rain would probably taper off Monday, but the weather presented another challenge - fog.
On Sunday, authorities added 12 counties to a presidential disaster declaration, increasing the total to 15. Federal officials provided food, water, cots and generators, bolstering the state and local response.
People in the 15 counties can also apply for help from the Federal Emergency Management Agency. Those counties cover 4 million people.
Separately, President Barack Obama on Saturday declared a major disaster for Boulder County. That step makes it easier for flood victims to get help for temporary housing and low-cost loans to cover uninsured property losses.