LOUISVILLE, Colo. (AP) -- Search teams looked for two missing people in the smoldering debris from a massive Colorado wildfire while people who escaped the flames sorted through the charred remnants of their homes to see what was left.
Investigators were still trying to determine what caused flames to tear through at least 9.4 square miles (24 square kilometers), leaving nearly 1,000 houses and other buildings destroyed in suburbs between Denver and Boulder.
The inferno broke out Thursday, unusually late in the year following an extremely dry fall and amid a winter nearly devoid of snow. Experts say those conditions, along with high winds, helped the fire spread.
Boulder County Sheriff Joe Pelle says authorities are pursuing a number of tips and had executed a search warrant at "one particular location." The sheriff refused to give details Sunday, including whether he thought the fire was arson.
"It's complicated and it's all covered with a foot of snow," Pelle said of the scene where the fire started. "The outcome of that investigation is vital -- there is so much at stake. We are going to be professional. We are going to be careful."
Rex and Barba Hickman sifted through the ashes of their Louisville home with their son and his wife.
Their son Austin cut a safe open with a grinding tool to reveal gold and silver coins, melted credit cards, keys and the charred remains of the couple's passports.
They evacuated with their dog, their iPads and the clothes on their back. Rex Hickman said he was heartbroken to see there was nothing left of their home of 23 years.
"There's a numbness that hits you first. You know, kind of like you go into crisis mode. You think about what you can do, what you can't do," he said. "The real pain is going to sink in over time."
The couple have to find a rental property and clothes in the short-term, and their insurance company told them Sunday it would take at least two years to rebuild their home.
"We know how fortunate we are," Rex Hickman said. "We have each other. We have great friends, wonderful family. So many people have got to be suffering much more than we are, and we feel for them."
While homes that burned to the foundations were still smoldering in some places, the blaze was no longer considered an immediate threat -- especially with Saturday's snow and frigid temperatures.
Authorities initially said everyone was accounted for after the fire. But Boulder County spokesperson Jennifer Churchill said the reports of three people missing were later discovered amid the scramble to manage the emergency. One was found alive, officials said Sunday.
Crews were still looking for a woman at a home in Superior and a man living near Marshall. Pelle said their homes were "deep in hot debris and covered with snow. It is a difficult task."
Other investigators were seeing if the missing people might have made it out, but not contacted their families or friends, Pelle said.
Colorado Gov. Jared Polis and federal emergency officials visited some of the damaged neighborhoods Sunday morning.
"I know this is a hard time in your life if you've lost everything or you don't even know what you lost," Polis said after the tour. "A few days ago you were celebrating Christmas at home and hanging your stockings and now home and hearth have been destroyed."
Of at least 991 buildings destroyed by the fire, most 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, Chuck E. Cheese, Tesla dealership, a hotel and the town hall.
The two towns are about 20 miles (30 kilometers) northwest of Denver and have a combined population of 34,000.
The flames stopped about 100 yards (90 meters) from Susan Hill's property in Louisville. She slept Saturday night in her home using a space heater and hot water bottles to stay warm since her natural gas service had not been turned back on.
She choked up as she remembered seeing the sky change color and recalled nervously sprinting out of town with her college-age son and the dog, cat and a fire box with birth certificates and other documents.
"I don't even know how to describe it," she said. "It's so sad. It's so awful. It's just devastating."