A 16-year-old autistic boy walked out of his Wyoming home 10 days ago and hasn't been seen since, despite a massive search involving local and federal agencies, drones, helicopters, K-9s and hundreds of volunteers.

Joseph Peterson walked out of his southeastern Natrona County home wearing a red hoodie and pajama pants between 11 a.m. and noon Nov. 10, according to the Natrona County Sheriff's Office. Officials believe the teen may not have been wearing shoes as he ventured into rough rural terrain during a Wyoming cold spell.

Natrona County Sheriff's Deputy Sean Ellis said the next day during a news conference that Peterson "is autistic who functions at a higher level, but is not self-sufficient and does not problem-solve at an age-appropriate level."

"Joseph has no concept of action versus consequence," Ellis said. The teen's decision to leave the house was a "misguided choice," and "foul play is not suspected," Ellis added.

Joseph Peterson. Natrona County Emergency Management

Sheriff's deputies who responded within 20 minutes of the report that Peterson left his house quickly discovered foot impressions, which were confirmed to be the teen's and indicated his "direction of travel leaving the house," according to the Natrona County Sheriff's Office spokesman, Taylor Courtney.

"We have no indication that he went toward the road or interstate looking for a ride," Courtney added.

Matching impressions were found Saturday "multiple miles away from the Peterson residence" and "provided a general direction of travel through very steep mountainous terrain," a statement from the sheriff's office said Tuesday. Though those tracks are thought to be days old, crews were focusing their efforts in the area where they were found. Peterson is 5'9 and weighs 120 pounds.

The Natrona County Emergency Management division, which is also involved in the search, warned Wednesday morning that the county, near the center of the state, would see whiteout conditions caused by snow and strong winds. Temperatures could dip to 13 degrees.

Authorities initially asked community members to stay away from the search area surrounding Peterson's home, but encouraged people who wanted to help to donate water and high-calorie food for the crews from more than a dozen county, state and federal agencies.

By the second day of the search, food and water were no longer needed, following an overwhelming volume of donations, and volunteers were allowed to join the search. Hundreds have helped authorities cover more than 240 square miles since.

Volunteers are asked to check in with a command post so that searched areas and structures are documented, officials said.

Horses, K-9s, fixed-wing aircraft, drones and helicopters are also being utilized in the desperate effort to locate the teen. "We’re trying to find Joey alive, and that's what we want to do," Courtney said.