LYONS, Colo. — Gerald Guntle dials his sister’s home multiple times a day, desperate to find out if she survived the widespread flooding that shattered the Rocky Mountain foothill town of Lyons, but the phone just rings and rings.
‘‘If there was no phone service, I wouldn’t expect to keep getting ringing. That’s what has me scared,’’ said the Tucson, Ariz., man, whose sister is among hundreds of people listed as missing in a disaster that is already confirmed to have killed as many as eight people.
Officials hope the number of missing will drop rapidly as communications are restored and people are evacuated throughout the region, as it did in Larimer and Boulder counties, where some 487 people dropped off missing-persons list over the weekend.
‘‘You've got to remember, a lot of these folks lost cellphones, landlines, the Internet four to five days ago,’’ Governor John Hickenlooper said on NBC’s ‘‘Today’’ show. ‘‘I am very hopeful that the vast majority of these people are safe and sound.’’
But faced with a lack of information, friends and relatives are struggling to avoid thoughts of worst-case scenarios.
Those searching for loved ones received a bit of good news early Monday afternoon when morning rains cleared and helicopter searches and airlifts resumed.
Ten military helicopters took off from Boulder Municipal Airport after being grounded most of the morning because of rain and clouds.
Colorado National Guard Lieutenant James Goff said 19 helicopters are available for search-and-rescue operations.
And the break in the rains allowed some weary evacuees to return home, but the receding waters revealed only more heartbreak: toppled houses, upended vehicles and a stinking layer of muck covering everything.
Residents of Hygiene returned to their small community east of the foothills to find mud blanketing roads, garages, even the tops of fence posts. The raging St. Vrain River they fled three days earlier had left trucks in ditches and carried items as far as 2 miles downstream.
‘‘My own slice of heaven, and it’s gone,’’ Bill Marquedt said after finding his home destroyed.
Residents immediately set to sweeping, shoveling, and rinsing, but the task of rebuilding seemed overwhelming to some.
‘‘What now? We don’t even know where to start,’’ said Genevieve Marquez.
In Estes Park, a tourist haven that serves as a first stop for many people entering Rocky Mountain National Park, Tony Bielat was searching for information about an elderly man who lives alone in nearby Glen Haven, where cabins and boulders washed down a swollen river. ‘‘The problem is no one knows who has been rescued,’’ Bielat said.
Officials were wading through the rubble in Glen Canyon, checking every structure in the town one by one.
Precise accounting of the missing remains elusive, with state and county agencies sometimes reporting conflicting totals. Colorado officials listed 1,253 people missing statewide at one point Monday and then updated it to 658 later in the afternoon.
Most of the missing were in Larimer and Boulder counties, which lie north of Denver and are dotted with self-reliant mountain hamlets where privacy-conscious residents live in remote homes difficult to access even in ideal conditions.
Boulder County has assigned 10 police detectives to search for the missing.
Officials are struggling to gauge how many people might actually be in danger as they field hundreds of calls from relatives, friends, estranged siblings, and also near-strangers.
In the mountain town of Lyons, stranded residents were unsure how to communicate their status. Telephone landlines were knocked out as floodwater rushed in Wednesday, and most people’s cellphones died long ago.
One man drove with his young son past the shuttered shops on a muddy and abandoned Main Street searching for guidance.
‘‘Do you need something?’’ shouted Glenn Scott, who was walking his two golden retrievers. It’s become the town’s new greeting.
The man said he was looking for FEMA headquarters to let officials know the pair were OK so they would not be listed among the missing.
But the only official seen around town that day was a local emergency worker telling residents it was their last chance to evacuate.
Guntle is hoping his sister and her two children — his only family now that his parents have passed away — are among the holdouts who have chosen boiled water, pantry items, and isolation over homelessness.
He called the shelter for displaced Lyons residents on Friday and was told his sister had not come in. He called 10 more times that day, but could not get through again.
‘‘I wish they had a list of people who are OK,’’ he said.