(CNN) -- A husband and wife died and another person was missing in a fast-moving Colorado wildfire that has scorched 4,500 acres in a mountainous area near Denver, officials said Tuesday.
Fueled by high winds and dry conditions, the fire has destroyed or damaged at least 23 structures, the Jefferson County Sheriff's Office said. None of it was contained, but it had not grown much Tuesday.
Pre-evacuation notices also were issued to 6,500 homes, meaning residents might have to leave.
Jefferson County Coroner John Graham identified the victims as Samuel Lucas, 77, and Linda Lucas, 76. Linda's remains were discovered at their residence first; Samuel's remains were recovered Tuesday. Although he didn't have exact causes of death, Graham said he suspects they were fire-related.
"They were found very close together. One was found outside; one was found inside," Jefferson County spokeswoman Jacki Kelley said.
Officials were trying to determine why the couple had not left the fire zone by Monday night.
Kelley provided little information on the missing person.
"It is a woman who lives within the area that was pretty heavily damaged," she said.
Kelley said emergency workers contacted 900 households earlier. Many were evacuated, and 25 people stayed in a shelter overnight. Some animals were removed from the area, but many others, including goats, alpaca and sheep, were left behind. First responders will try to rescue them Tuesday.
About 200 firefighters were on the scene Tuesday afternoon, Kelley said. Officials expect to have 450 working shifts by the end of the day.
"We still need lots of boots on the ground," Kelley said.
The fire was a controlled burn that crept outside the perimeter and swept through the area rapidly. March has been extremely dry in the area, and the land is parched after a winter with little snow.
Authorities are investigating the fire's origin.
A Lockheed P-2 heavy air tanker, capable of carrying more than 2,000 gallons of slurry, foam or water, joined the aerial firefighting efforts Tuesday, according to CNN Denver affiliate KWGN.
CNN's Phil Gast and Darrell Calhoun contributed to this report.