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 could n'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 ca n'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 .
NEW : 140 structures destroyed , 24 damaged . NEW : 2 people killed by falling debris from the tornado 20 were initially reported missing , but 16 people were located . Gov . Bill Ritter has declared a state of emergency .