Three people are still missing after devastating Colorado wildfires destroyed hundreds of homes, authorities said.

       Thousands of people were forced to evacuate in Boulder County on Thursday when high winds and dry conditions helped fuel two fast-spreading wildfires, the more destructive of the two being the Marshall Fire.

       Hart Van Denburg/Pool via AP

       A Boulder County neighborhood smolders after it was was destroyed by a wildfire, Dec. 31, 2021.

       No casualties have been officially reported, though three people have been reported missing in the region of the Marshall Fire, Boulder County Sheriff Joe Pelle said during a press briefing Saturday.

       "I suspected we would have loss of life just based on the size of this fire, the speed and the ferocity," Pelle said. "I think it's miraculous that it is three and not 100 or hundreds. So I'm grateful for that, but I'm also extremely sorry for the families."

       Two people were reported missing in the town of Superior, while one person is missing in the Marshall area, Pelle said.

       MORE: Hundreds of homes lost amid fast-spreading Colorado fires

       Their homes have been destroyed, and search and recovery efforts have been further impeded after 8 inches of snow fell on the structures, the sheriff said.

       First responders plan to bring in cadaver dogs on Sunday to help find potential human remains in the homes, he said.

       "We unfortunately believe these are going to turn into recovery efforts," Pelle said.

       Michael Madrid/USA Today via Reuters

       A man walks through a destroyed neighborhood after the wildfire in Louisville, Colo., Dec. 31, 2021.

       The Marshall Fire has destroyed 991 total structures and damaged 127, based on preliminary assessments, authorities said. In the city of Louisville, 553 structures were destroyed and another 45 were damaged. In Superior, 332 structures were destroyed and another 60 were damaged.

       Parts of Boulder County are still under evacuation due to "active hot spots, downed power lines and damaged trees at risk of falling," according to the Boulder Office of Emergency Management.

       MORE: 'Miraculous': No casualties reported in devastating Colorado wildfires

       Authorities are still working to determine the cause of the fires, which were first suspected to be sparked by downed power lines. The sheriff's office executed a search warrant on a property based on a tip it recently received, said Pelle, who did not provide any further information on that case.

       "We're looking at any cause for the wildfire," he said. "If it turns out to be arson, or reckless behavior with fire, we'll take appropriate actions."