Boulder Neighborhood Center of Marshall Wildfire Investigation, Unknown if Arson Suspected

Amid their investigation into the cause of the destructive Colorado wildfire that erupted Thursday, authorities are focusing on an area near Boulder where a civilian took a video of a burning shed the day the blaze began, according to Boulder County Sheriff Joe Pelle.

A sheriff's official who spoke on condition of anonymity said that several properties were being investigated and authorities conducted a search warrant over the weekend, but declined to say whether he believed arson was to blame for the blaze.

The Marshall Wildfire destroyed nearly 1,000 homes and structures and spurred tens of thousands of people to evacuate their homes in the suburban area between Boulder and Denver. Crews searched two locations for any human remains as two people remained missing in the fire's aftermath.

The sheriff's official said one of the homes under investigation is in the Marshall Mesa area, located about two miles west of the town of Superior, which was hit particularly hard by the fire and blocked off by a National Guard Humvee on Monday. Surrounded by dry open spaces and grasslands, Marshall Mesa overlooks several of the more heavily populated suburbs to the east that were ravaged by the rapid wildfire.

No downed power lines were found in the area, according to authorities. Experts from the FBI, the Bureau of Alcohol, Tobacco, Firearms and Explosives and the U.S. Forest Service joined the investigation, and dozens of people have already been interviewed, Pelle said.

Declaring that "the stakes are huge," Pelle said he would not release details on the probe until he was ready "to announce some progress — perhaps that may be a week, perhaps that may be a month."

Getting it right, he told reporters Monday, was "more important than the urge for speed that a lot of folks are feeling right now."

Experts say the winter fire was rare but that similar events will become more common as climate change warms the planet and suburbs grow in fire-prone areas. The blaze broke out following months of drought that included a dry fall and a winter with little snow so far.

In the search for the missing, crews were looking for a woman in the town of Superior and a man from the nearby community of Marshall.

Louisville Police Chief Dave Hayes said authorities used cadaver dogs to re-check destroyed properties as a precaution. He said no one was reported missing in the heavily damaged city, but that "doesn't mean we won't find something." Hayes told reporters after the briefing that he lost his own home and was wearing a change of clothes he asked someone to buy for him.

While homes that burned to the foundations were still smoldering in some places, the blaze was no longer considered a threat, especially after a blanket of snow and frigid temperatures tampered flames Saturday.

Most of the 991 buildings destroyed by the fire were homes. But the blaze also burned through eight businesses at a shopping center in Louisville, including a nail salon and a Subway restaurant. In neighboring Superior, 12 businesses were damaged, including a Target, a Chuck E. Cheese pizzeria, a Tesla car dealership, a hotel and the town hall.

Among the homes that were still intact, utility crews went door to door to check if natural gas and electricity could be safely restored.

"What a relief," uttered Louisville resident Carl Johns as a utility worker turned on a gas valve and went inside Johns' home of 21 years to make sure appliances were lighting up. He had been living with friends since Thursday, when police drove through the neighborhood and urged everyone by loudspeaker to evacuate.

Some of his neighbors weren't so lucky. Down the street stood a row of burned homes.

"That just blows me away," Johns said. "The houses aren't there, and you can't recognize your own block."

The Associated Press contributed to this report.