BOULDER, Colo. — Another round of storms swept into battered Colorado on Saturday as weary residents reeled from days of death and destruction wrought by historic flooding.
Evacuations continued at a frantic pace as rescuers encountered swamped roads, inundated homes and the dark forecast of more rain to come.
The flood zone has grown to cover portions of an area nearly the size of Connecticut.
"It is a sinking feeling when you realize that when some people call ... we are not going to be able to get to them," Boulder County Sheriff Joe Pelle said. "But we are making great progress."
Airlifts were to continue Sunday with helicopter crews expanding their searches east to include Longmont, Fort Collins and Weld County.
Pelle said more than 170 people unaccounted for in the Boulder area were not considered missing yet, though they had not contacted family members.
One woman is presumed dead and about 350 were unaccounted for as officials discovered the enormity of destruction the floods brought to Larimer County and an unknown number of homes, The Coloradoan reported Saturday.
Meanwhile, the sun peeked out over the debris-strewn area, providing a brief respite before clouds and more rain crept into the area. Days of torrential rains have left at least four people dead.
Two fatalities were identified by the Boulder County coroner Saturday as Wesley Quinlan and Wiyanna Nelson, both 19.
Authorities believe the couple died when they were swept away after driving into floodwaters and then leaving their vehicle. Their cause of death is under investigation.
The missing woman could become the fifth confirmed death. Witnesses saw floodwaters from the Big Thompson River destroy her home in the Cedar Cove area, Larimer County sheriff's spokesman John Schulz said.
"We're sure there are going to be additional homes that have been destroyed, but we won't know that for a while," Schulz said. "I expect that we're going to continue to receive reports of confirmed missing and confirmed fatalities throughout the next several days."
Many of those driven from their homes may not be able to return for weeks. Early Saturday, National Guard helicopters evacuated hundreds of residents from Jamestown, a mountain town northwest of Boulder.
By Saturday night, 1,750 people and 300 pets had been evacuated from Boulder and Larimer County, according to National Guard Lt. James Goff.
"We are not going to force anyone from their home," Pelle said Saturday, but he noted that "if they don't come today, we want people to know that we may not be able to get them tomorrow."
Thousands of people have fled homes in an area that normally sees less than 2 inches of rain in all of September but has been deluged by more than 14 inches this week alone, the National Weather Service said.
Rain was expected to start up again in the mountains and foothills, with up to 2 inches forecast to fall overnight.
"We don't expect quite the level of intensity we've seen the last few days, but the soil is saturated, so it won't take much to do damage," Scott Entrekin, a weather service meteorologist in Boulder, told USA TODAY.
Entrekin said the storms, which have brought flooding in some areas that "we've never seen before," could ease Sunday. "Hopefully after that we will start drying out," he said.
Pelle lauded federal emergency officials for their quick response, providing material and personnel on the ground. A day earlier, President Obama declared an emergency for three counties in Colorado, and ordered federal aid to supplement state and local response efforts.
Federal Emergency Management Agency Administrator Craig Fugate said a FEMA assistance team was coordinating with state and local officials.The U.S. Transportation Department said it would immediately provide $5 million in emergency relief funds to help Colorado cover the costs of repairing roads and bridges.
Flood warnings remained in effect Saturday from Denver to the Wyoming border. Parts of New Mexico and Texas also were dealing with torrential rains, flooding and evacuations.
In neighboring New Mexico, state police on Saturday reported the first death related to massive flooding in the state this week from record heavy rains and overflowing rivers. The man died after his vehicle washed into a ravine covered in mud near the Elephant Butte dam.
About 15 miles north of Boulder, the Colorado National Guard began evacuating 2,500 residents of Lyons at daybreak Friday.
"There's no way out of town. There's no way into town. So, basically, now we're just on an island," said Jason Stillman, 37, who was forced with his fiancée to evacuate their home in Lyons after a nearby river began to overflow into the street.
Pelle said he expects the number of those unaccounted for — and the death toll — to rise, because most of the western part of the county remained inaccessible.
"The things that worry us are what we don't know," he said. "We don't know how many lives are lost, we don't know about homes lost."
Interstate 25, the state's main north-south highway, north of Denver to the Wyoming border has reopened after being closed for more than a day. In neighboring Weld County, where more acres of farmland have been turned into lakes and more than 140 roads have been closed, Commissioner Bill Garcia called the flooding an "unprecedented event,"The Greeley Tribune reported.
Colorado Gov. John Hickenlooper said the state has lost "a great deal of infrastructure,'' although an exact assessment of flood damage could take weeks.
