A 3-year-old North Dakota boy who disappeared for nearly seven hours was later found under the protective cover of the family's pet dog, authorities said.

Carson Urness disappeared from his family's 10-plus acre property in Cooperstown, North Dakota, around 7:30 p.m. Monday after being let out to play while his mom worked inside the home, the boy's father told ABC News.

"She checked on him again at 7:30 and he was gone," Carson's father, Brock Urness, said of his wife, Courtney, who was inside taking care of the couple's 11-month-old daughter while Carson played.

"She looked around frantically for about 30 minutes and then called me," Urness said. "And I said, 'Well, where's Cooper?' and she said, 'Cooper is not here either.'"

Cooper is the family's dog - a German Shepherd, Labrador and Golden Retriever "mutt," as Urness calls him - that the family adopted three years ago after he was left on the side of the road near a relative's home.

The Urnesses searched for Carson until 8:30 p.m. when they called 911. Less than 30 minutes later, the local police and fire departments had launched an aerial and ground search for Carson, aided by 200 neighbors, family and friends from Cooperstown, population about 800.

"They had an airplane here searching for him and 60 four-wheelers and people looking on foot and didn't find anything," Urness said.

Just before officials planned to call off the search for the night, around 2:30 a.m., officials decided to send out one last four-wheeler for a final sweep of the property.

"That four-wheeler found him about a mile away from our house, in the middle of one of our fields by a pasture," Urness said. "Carson was in tall grass but when they shone lights down to sweep it, the dog stuck its head out."

Carson was found safely underneath Cooper, who was laying on the boy, presumably to protect him from the 40-degree temperatures that night.

Both Cooper and Carson were uninjured, save for Carson's cold feet, which were the only body part of his that Cooper did not cover.

"Carson told his mom that Cooper stayed on top of him and kept him safe and warm," Urness said. "He told her that he was a little scared when it got dark because he doesn't like the dark."

Urness believes his son ended up one mile away from their home after watching Urness leave the property on a tractor, heading east.

"I think he saw us from his bedroom window leaving and he wanted to go where we were so he walked," Urness said. "Cooper doesn't leave the yard but since they're best friends he went and followed him."

The aerial search gave the family a false sense of hope early on when the helicopter picked up activity but it turned out to be a skunk. Urness said he and his wife became really worried when a search dog did not pick up any scent of Cooper, but were happy the family dog was there to protect their son.

"We're very thankful for the police and local fire department here and all the people with horses and four-wheelers and the walkers," Urness said. "We're very grateful that they all came and looked and helped us."