CNN reported that James Glanton, 34, and Christina MacIntee, 25, are missing, along with a 10-year-old, two 4-year-olds and a 3-year-old, the Pershing County Sheriff's Office said. The six set out Sunday for Seven Troughs mountain range and haven't been seen since.
Fears for their safety grew as the temperature was expected to hit 6 below zero Tuesday night.
Temperature dips 12 days before official winter start
Amanda Fitzpatrick, mother of the 10-year-old, Shelby Fitzpatrick, told that she'd joined the search. Rescue teams have tried to stay positive, she said. "It's been extremely hard, probably the hardest 24 to 36 hours of my life," she said. "It's my baby girl."
At least 15 people have died because of the weather, mostly in traffic accidents. Eight died in Oklahoma alone, including a 6-year-old who fell through ice on a creek in Tulsa and men who died in house fires in Westville and Tulsa, the state Department of Emergency Management reported on Monday.
Temperatures across the country are expected to stay very low, usually 10 to 20 degrees below normal, for the rest of the week in regions struggling after days of wintry weather, according to the National Weather Service.
Dallas is still trying to shake off the effects of a weekend ice storm and had about 20,000 customers without power on Monday, according to power company Oncor. Anchorage, Alaska, has been warmer than St. Louis and Denver.
"It's very unusual," CNN meteorologist Dave Hennen said. "This literally spreads across the entire U.S., and we're 12 days from the official start of winter."