(CNN) -- [Breaking news update at 3:11 p.m. Tuesday]
Rescuers have located two adults and four children who have been missing since they went to play in the snow Sunday in a mountainous area in northwest Nevada. They were found safe and in fairly good condition, according to the Pershing County Sheriff's Office.
[Original story, posted at 3 p.m. Tuesday]
Crews lose phone ping, continue search for 6 lost in Nevada bitter cold
(CNN) More than 200 people scoured a vast frozen range of Nevada spanning 6,000 square miles Tuesday for two adults and four children who went missing in their Jeep on a snow outing two days earlier, authorities said.
The disappearance of a man with his two children and a woman with her niece and nephew was among the most dramatic developments in the Arctic-like weather shocking much of the Lower 48 states.
Officials in Nevada remained undaunted despite the fact they no longer received pings off the cell phone of the missing persons, said Sheila Reitz of Pershing County Sheriff's Office.
On Monday, authorities had been encouraged when they were able to receive of couple of pings from the phone of James Glanton, 34, officials said. Cell service is spotty because the area is so remote.
Also missing are Glanton's two children and Christina MacIntee, 25, along with and her niece and nephew. The children range from 3 to 10 years old, the sheriff's office said. They all set out to play in the snow in the Seven Troughs mountain range Sunday and never returned.
On Tuesday morning, a massive search involving vehicles, planes and helicopters was unable to sight the missing group, Reitz said.
Worries ran high as thermometers plunged below zero overnight.
"The temperatures out here are very cold, and we'd like to bring a successful end to this," Sheriff Richard Machado said on a snow-packed country road. "We'd like to find them, just as soon as we can."
Family friend Joan Weagant was also on the scene. "We just got to find them. We've known them forever, you know. And those little tiny kids can't be out there in the cold. None of them can be out there in the cold," she said.
Amanda Fitzpatrick, mother of 10-year-old Shelby Fitzpatrick, one of the missing children, has joined the search in the bitter cold.
"It's been extremely hard, probably the hardest 24 to 36 hours of my life," she told CNN's Piers Morgan. "It's my baby girl."
More snow and ice
The pre-winter wintry weather isn't over yet. Temperatures in storm-stricken parts of the country are expected to stay about 10 to 20 degrees below normal for the rest of the week, the National Weather Service said.
More sleet, snow and freezing rain will cover Washington on Tuesday morning, and a swath of 2 to 6 inches of snow is expected to fall Tuesday from Virginia to the New England coast, forecasters said.
Philadelphia can expect to get 3 to 5 inches of snow on Tuesday; New York City, a little less than that.
The storm will finally leave the East Coast late Tuesday, but the mercury won't rise above freezing until at least Friday, the National Weather Service said.
Elsewhere across the country, Portland, Oregon, and Chicago will see snow and freezing rain this week.
Even St. Louis has been colder than Anchorage, Alaska.
"It's very unusual," CNN meteorologist Dave Hennen said. "This literally spreads across the entire U.S."
Choked off travel
At least the nation's airports are getting back to normal. The websiteFlightaware.com says about 775 flights have been canceled for Tuesday. That's down from the 1,900 flights canceled on Monday and 2,800 on Sunday.
But road conditions have been treacherous. At least 15 people have died from weather-related incidents in the past several days, mostly in traffic crashes. Eight died in Oklahoma alone, state officials said.
And the hazardous conditions in northern Nevada have many concerned about the missing children and adults.
"If there's one thing you should learn from the lessons of these people, never let your tank below a half a tank (of gas) in the winter," CNN meteorologist Chad Myers said. "You might need that for the electricity, for the power, for the heat in that car."
CNN's Randi Kaye and Judson Jones contributed to this report.
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