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Boulder, Colorado (CNN) -- Cloud cover, cooler temperatures and a little bit of rain assisted firefighters battling a wildfire west of Boulder, Colorado, authorities said Wednesday.
Four people remained unaccounted for, authorities said at a late afternoon press conference.
"We can hope [weather factors] will be a positive influence on helping firefighters getting some more work done," said spokeswoman Laura McConnell of the Rocky Mountain Incident Management Team
Authorities initially had reports that 20 people were missing, said Sarah Huntley, a spokeswoman for Boulder's Office of Emergency Management. Sixteen of them were subsequently located.
Of those still missing, some "were people who did not evacuate," Boulder County Sheriff's Office Cmdr. Rick Brough said. Police were contacting their relatives and were also conducting welfare checks at their homes, Brough said.
About 140 structures, which includes residences and other buildings, were destroyed, Brough said. Twenty-four were damaged.
Officials said they had no containment information on the fire and did not yet know its cause.
Some residents were concerned they couldn't check on their homes Wednesday, but Brough said it was too risky too allow travel into the area.
"We have active fire, he said. "We can't let people up yet."
Officials have established an emergency shelter and victim assistance center.
The list of damaged homes was posted online Tuesday night. The list will be added to as authorities continue to assess damage left by the blaze.
"These addresses were determined from only 5 to 10 percent of the burned area, as that is the only area that could be safely surveyed on Tuesday," the list said.
An infrared flight allowed authorities to better map the fire, and its size has shrunk from the 7,100 acres reported earlier to 6,388 acres, said McConnell. Twenty-four engines and 300 firefighters were on scene Wednesday, and several aircraft were also being used to battle the blaze, she said.
A community meeting is planned for Wednesday night, Brough said.
Brough said Tuesday night that flames had spread throughout the Fourmile Canyon area west of the city.
After an anxious day, evacuee Paul Gatza of Sunshine learned late Tuesday that his house had been spared.
"Fortunately, we just got visual confirmation ... that we're still standing for one more night, and [Wednesday] will be another new, long day," he said. "It's a matter of trying to gain little pieces of information from firefighters and firefighters' spouses, and whoever else we can get reliable news from."
Colorado Gov. Bill Ritter declared a state of emergency Tuesday as the size of the wildfire more than doubled.
Ritter said the state was throwing $5 million into the battle to save homes and forests in the canyon.
"It is important right now for people who've been evacuated to just be patient," Ritter said after a tour of the area. "This is a very volatile situation, it would be fair to say. There is a fire line. They are doing all they can to contain the fire line. At the same time, there are a fair number of embers that are also starting smaller fires."
Ritter said he saw "entire hillsides" burned by the flames, along with numerous structures.
"It's not safe for people to return to their homes, because as we drove up there, you go from a place that is relatively safe, and then suddenly, you'd see a spot fire burning on the side of the road," he said.
Boulder County Sheriff Joe Pelle accompanied the governor on his tour of the area and said the fire had "literally exhausted our local resources and management team."
"But we have a good and healthy amount of people in place now learning everything they need to know about the fire," he said.
The sheriff said Tuesday his department was investigating a report that the fire may have started when a car hit and ruptured a propane tank.
"That's the best information I have right now, but that's part of what that investigative team is doing for me today, is trying to lock all that down and confirm it," he said.
Pelle said that authorities had evacuated 70 subdivisions and made nearly 8,000 notifications. No injuries have been reported.
CNN's Ed Payne, Melanie Whitley, Georgette Knuckles and CNNRadio's Matt Cherry contributed to this report.