When Sarah Klebs' daughter Caroline complained of a headache last Saturday, followed by her son, Gavin, vomiting, she assumed the family had caught the flu, the Alaska Dispatch News reported.
But a day later, after the family was pulled out of their recreational cabin near Big Lake, she realised it wasn't a virus - it was carbon monoxide poisoning, said news.com.au.
"How would you know?" Ms Klebs told the Alaska Dispatch News. "Prior to this, I never would have thought about it."
The propane-powered appliance at their cabin had started leaking carbon monoxide - an odourless gas - investigators later determined.
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Ms Klebs and 8-year-old Caroline recovered, but Gavin did not. The 10-year-old was found in the main area of the home.
Ms Klebs' husband, Matt Klebs, is a mechanical contractor and said he thought the refrigerator was in good condition. He even he did regular maintenance on it.
"I'm in the business to keep this from happening," he said.
Now the heartbroken couple are speaking out about what happened to warn other families about the hidden danger of carbon monoxide poisoning.
They are encouraging families to install a carbon monoxide detector in their home. They said they did not yet have a detector in the 25-by-30-foot cabin they use frequently, but told the Alaska Dispatch News they had planned install one in winter when they'd be spending more time indoors.