Colorado authorities said the investigation into last week's massive wildfire had become more complex after a snowstorm ripped through the area where the fire started on Saturday.
Local authorities said they carried out a search warrant at "one particular location" where they believe the fire first began but the scene is now covered in a foot of snow, making the investigation more complicated, said Boulder County Sheriff Joe Pelle.
"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," Pelle said.
Local authorities are looking into multiple tips about the cause of the fire but Pelle wouldn't say if he believed the fire was set intentionally or was an accident.
Nearly 1,000 homes and other buildings were destroyed by the fire which spread through 9.4 square miles between Denver and Boulder.
Authorities are still looking for two missing people, a woman near the town of Superior and a man from Marshall. A third was found alive on Sunday, according to officials.
Investigators are trying to figure out if the missing people may have made it out alive but have yet to reach out to friends and family, Pelle said.
The inferno broke out last Thursday, unusually late in the year following an extremely dry fall and amid with hardly any snow. Experts say those conditions, along with high winds, helped the fire spread.
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 had evacuated with their dog, their iPads and the clothes on their back and Rex Hickman said he was heartbroken to discover that 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 frigid temperatures and a snowstorm on Saturday.
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 of the missing people was found alive, officials said Sunday.
Colorado Governor 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."
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, 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 keep warm because her natural gas service had not been turned back on.
She choked up as she remembered seeing the sky change color and recalled nervously fleeing 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."
The Associated Press contributed to this report.
