The National Guard had rescued more than 1,200 people in Boulder County by Saturday afternoon, Lt. Col Mitch Utterback said.
In Larimer County, there were 46 medical rescues on Friday alone, the sheriff's office said.
Pelle said authorities have to be "realistic" about the chances that the death toll will rise as rescuers penetrate further into isolated areas.
The four confirmed deaths included a woman who was swept away when she got out of her car Thursday in Boulder County. A man jumped out of the car to save her. Both drowned. Authorities recovered both bodies, Pelle said.
Another body was found in a collapsed home in Jamestown in the same county. Rescuers recovered another body on a roadway in Colorado Springs in El Paso County.
In Denver, rushing waters swept a man into a drainage pipe with his dog. Both were saved after traveling two blocks in the water, police said.
President Barack Obama declared an emergency for Boulder, Larimer and El Paso counties, FEMA announced Friday. The declaration allowed FEMA to bring in four rescue teams, the largest ever deployment in Colorado, officials said.
The clear skies allowed for an uptick in evacuations Friday and earlier Saturday.
National Guard troops using "high-profile" trucks to wade through water evacuated 550 people from the Boulder County town of Lyons, CNN affiliate KUSA reported.
It had been cut off since the flooding began Wednesday night -- without water or sewer service, in many cases without electricity.
Melinda Villa was stranded in her apartment with her 1-month-old baby in the inundated town. She had no phone service, no water and was running out of formula and food.
Then the National Guard arrived.
"It just really felt like God came down and saved us," she said.
Some had to rescue themselves.
Catherine Smith and Mandy Stepanovsky lived in a part of Lyons that is accessible only by bridges.
"When those became compromised -- one bridge completely blew out and the other one was very much impassible -- we started looking at other options," Smith said.
So the couple decided to hike for 2 miles to safety -- with their 8-month-old toddler in their arms. Walking was the only way out.
They hiked to Smith's brother's house, where they showered and ate a meal before the weather caught up with them again.
A mudslide suddenly brought mud, debris and water through the house, Smith said. They were forced to run to higher ground.