The governor of Colorado on Friday ordered the National Guard into a town outside Boulder in hopes of evacuating hundreds of people feared stranded by record floods that were ravaging the state for a third day.
Gov. John Hickenlooper said it had to be "the largest storm that I can imagine in the state's history."
The evacuation, for the town of Lyons, outside Boulder, will require about 100 soldiers from the Colorado National Guard and more than 20 trucks, a U.S. military official told NBC News.
Unusual late-summer downpours raked the state again, shattering a 73-year record for September rain in Boulder. About 4,000 people were ordered evacuated there Thursday as water surged out of a nearby canyon.
"There's so much water coming out of the canyon, it has to go somewhere, and unfortunately it's coming into the city," Ashlee Herring, a spokeswoman for the Boulder emergency management office, told Reuters.
The nearby city of Longmont was inundated after a river jumped its banks. About 7,000 homes there were under orders to evacuate.
Hickenlooper said that the state Department of Transportation had ordered traffic restricted to essential only for four counties to the north and west of Denver. Emergency vehicles were having a tough time getting around, he said.
At least three people have died in flash floods in the area, and at least 17 were missing Friday.
Holly Stetson was waiting for word on her father, an 81-year-old retired elementary school teacher who Stetson said was probably trapped in his house in Lyons.
Stetson told KUSA, the NBC affiliate in Denver, that her mother evacuated early Thursday morning, but said the father probably stayed behind. Stetson said she "had a visual" of the house that showed 2 feet of water on the outside.
"Just hoping for a great outcome," she said. "I feel like he's got lots of common sense. He was a Boy Scout scout leader for many, many years. He knows what to do if we got stuck in the house. We're just putting our faith in that."
There was some good news: What authorities described as a 30-foot surge of water, mud, rocks and debris dissipated before reaching the outskirts of Boulder.
The surge flattened out as the canyon became less steep toward the city and by the time it arrived at Boulder Creek it was not nearly as severe as initially feared, officials said.
Colorado State University, in Fort Collins, said it would close for the day, not because of flooding on campus but because the surrounding roads were difficult if not impossible to navigate.