Flash flooding in Colorado has killed at least three people, left some residents stranded and forced hundreds to seek higher shelter. NBC's Miguel Almaguer reports.

Scores of residents of Boulder, Colo., sheltered in a local YMCA late on Thursday as the region washed by days of rain and now flash floods braced against the continuing storms that have already claimed three lives.

At 11:15 p.m. MT, the Boulder Office of Emergency Management issued two emergency alerts to 8,000 phone numbers for residents along Boulder Creek, telling some to move to higher ground without crossing the creek, others to shelter in place but to move to higher floors if possible.

Five minutes later, the OEM said a resident had called to say a "large surge of water, mud, rocks and debris, including cars, about 30 feet deep is heading down Fourmile Creek. "The flow was expected to reach Boulder Creek about midnight, the bulletin said, and residents were "warned to go to higher ground."

Fire Chief Gerry Morrell in Lafayette, Colorado released video of crews rescuing a man from a car trapped in flood waters.

"It's insane right now, I've lived in Colorado my whole life, and this is nothing that I've ever, ever seen before," said Andra Coberly spokesperson for the YMCA in Boulder. "Streets were turned into rivers and streams were turned into lakes."

Hers was a common story in the storm-swept region, even as forecasters said the rains were likely to continue to pour down on saturated grounds through Sunday.

The torrential downpours that lashed parts of Colorado drove hundreds of people from their homes, shut down Boulder and the nearby university, and had police and fire responders scrambling all day as they worked to help stranded residents in what they described as a still-developing disaster.

The bad weather also hampered rescue efforts, making it impossible to get search and rescue helicopters into the air, officials said at a press conference on Thursday afternoon, and increasing the dangers for responders who tried to make their way into some of the most affected areas. About 6.8 inches of rain fell over the city in a 24-hour period, according to the National Weather Service.

In the foothills north of Boulder, Colorado, Lee Hill Drive has been hit hard by floodwaters. NBC's Joe Fryer spoke with some of the residents.

The first death was reported near Jamestown, according to officials, and was thought to be because of a building collapse. Another person was found dead on Linden Drive in Boulder County, officials said. The Colorado Springs Fire Department reported a third death on Thursday morning after a body was recovered near Interstate 25, when authorities were patrolling the area around 5:30 a.m. local time.

One person who was inside a vehicle that was swept away in Boulder County was considered missing, local media reported.

Throughout the surrounding area, some residents struggled to find their way to safety as floodwaters threatened and officials warned everyone to stay indoors and far from waterways.

Sally Truitt, 51, was at home on her farm in Lyons, Colo., when she got a call around 1 a.m. saying they were under a mandatory evacuation order, and had to get out fast. Along with five other people and eight dogs in three cars, she fled home looking for safety from the rushing St. Vrain River, and not a moment too soon.

"As soon as we pulled out of the driveway, there was a breaching of the river nearby," Truitt said. "We just barely made it out in time. We were lucky."

Truitt's 17-year-old daughter Early Ferguson described going back early Thursday morning to see what was left.

"We went to a cliff above my dad's house and it was just completely flooded," the teen said. "It was like a river over my house. We could hear the dogs barking on the second floor. It was really scary."

"My daughter was just wailing and screaming," Truitt said. "It's so disturbing to see this home she was born in turned into this angry, raging river. It brought us all to our knees at that point."

National Guard arrive

Lyons, in Boulder County, was completely cut off from surrounding areas because of flooded roads, but the National Guard was able to reach there Thursday night and provide humanitarian assistance, NBC station KUSA in Denver reported.

The University of Colorado Boulder said on its Twitter account that its campus would be closed until officials could assess the storm damage, and some residences were evacuated. Between 400 and 500 graduate students, faculty, and staff are thought to be displaced from on-campus housing units, said university spokesman Bronson Hilliard. Forty campus buildings, or about 25 percent of the school’s facilities, have sustained some form of water damage. The school will remain closed through Friday.

“We are pleading with students and people on this campus to stay indoors,” Ryan Huff, a spokesman for the campus police, said at a press conference early Thursday morning. “It is dangerous out there.”

Hannah Harris, a sophomore at the university, said she stayed put as long as she could, but had to abandon her apartment about five miles from the school on Wednesday night as two inches of water flooded the floor. The toilets began to overflow around 1 a.m., she said, and dark water poured from the shower before she and her roommates decided to make their way to the Boulder YMCA – a mile-and-a-half drive that turned into a harrowing hour-long trek.

“It wasn’t too bad early in the evening; we didn’t expect anything to happen since we are a little bit on higher ground than campus,” Harris said. “Then everything started overflowing.”

Shelters have been opened for evacuated or displaced residents at the YMCA in Boulder, at elementary schools in Jamestown and Lyons, and at locations in Longmont and Nederland, according to Boulder’s emergency management office. There were about 40 people at the evacuation center in Boulder on Thursday morning, according to Coberly, the YMCA spokesperson, with more arriving throughout the day.

John Schulz , Public Information Officer of the Larimer County Sheriff's office in Colo., said a series of dams overflowed and one broke overnight, killing one, and threatening hundreds more.

“We’re also getting in calls from people who have been evacuated, people looking for their friends or family who they can’t get a hold of, so a lot of people are concerned in the area,” Coberly said.

President Obama late Thursday approved federal disaster assistance for Colorado, signing off on a request from Gov. John Hickenlooper.

100-year flood

The Boulder area was experiencing a 100-year flood, Robert Kimbrough of the US. Geological Survey, told the Daily Camera newspaper.

Boulder County Sheriff Joe Pelle described the status throughout the county on Thursday as a "continuing, very dangerous situation." Gov. John Hickenlooper approved a disaster declaration, and spokesman for the governor said in an email he was "actively involved" in the flood response efforts. Authorities blasted out regular alerts on social media and official websites as they evacuated areas including Big Thompson Canyon throughout the day.

"This is not your ordinary day, this is not your ordinary disaster," Pelle said. "All the preparation in the world … can't put people up those canyons while those walls of water and debris are coming down."

Water reached as high as first-floor windows in some parts of Boulder, a police and fire spokeswoman said. Dive teams were dispatched after cars were seen floating. Libraries, recreation centers and other Boulder facilities were closed, according to the city’s office of emergency management. Energy companies workers were trying to restore power after several flood-related outages according to the emergency office’s website.

“It may look OK in your neighborhood, but by the time you get on the thoroughfare to work, you may run into some real issues,” Pelle told the Daily Camera. “We’ve got cars in water and debris and manholes missing their covers literally everywhere in the county.”

University of Colorado Boulder spokesman Ryan Huff pleaded with students to not go outside in dangerous flood conditions as the school closes its campus.

The Denver Zoo announced it was shutting down because of the weather on Thursday.

In the city of Longmont, about 15 miles north of Boulder, a police officer went door to door encouraging residents to leave, saying “this is going to get worse,” the Longmont Times-Call reported.

As many as five dams were blown out by the torrential rain, and a dozen others overflowed but didn't have structural failures, the Denver Post reported.

North of Boulder, failing dams trapped one family on the second floor of their home up a washed-out country road, John Schultz, a spokesman for the Larimer County Sheriff's Office told the Post.

A county emergency worker who went to check on the family Thursday witnessed a wall of water smashing through the front door of the home and flood the first floor. The family of three huddled on the second floor awaiting rescue, Schultz said.

Every available fire and police official was out on the streets on Thursday, Boulder city spokeswoman Sarah Huntley said. Flood sirens have been activated along Boulder Creek, and if there are sudden flash floods, "the warnings are going to be short," Huntley said.

The deadliest flood in Colorado history occurred in Larimer County in July of 1976, when the Big Thompson River swelled its banks, killing 144 people and causing more than $85 million in damages, according to data compiled by the University Corporation for Atmospheric Research.

Christopher Nelson and Alexander Smith of NBC News and David Wyllie of BreakingNews.com contributed to this report. The Associated Press also contributed.

In this archival report from Aug. 3, 1976, NBC's Mike Jackson reports on the deadliest flood in Colorado history.

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