Authorities say it's a miracle a 5-month-old boy survived after he was found alive alongside his unresponsive parents in a house with life-threatening carbon monoxide levels.

The 19-year-old parents were found dead Wednesday morning believed to be from carbon monoxide poisoning in what was supposed to be a vacant Battle Creek, Michigan home. The baby was transported to the hospital for treatment.

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“We don’t know [how the baby survived] -- the grace of God," Detective Sgt. Todd Elliott of Battle Creek Police Department said in a press conference Wednesday. "Talking with medical personnel, with the levels of carbon monoxide that were in that house, the baby should’ve died."

In parts of the house, investigators' sensors showed levels of the gas more than twice the amount considered deadly.

“Just surviving in that concentration of carbon monoxide -- and this is coming from medical personnel -- it’s just amazing," Elliott said.

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A contractor working on the house found the child on an air mattress next to his parents and immediately called 911, according to police.

"This was a terrible accident where two young people died," Elliott said, adding that it is "unfortunately, a tragic reminder of a reason not to run a generator without proper ventilation."

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Investigators say there were no signs of foul play, and while no one was supposed to be staying in the home while it was being remodeled, they believe the couple didn't have a vehicle and decided to stay due to the conditions of the roads.

Child Protective Services is working to notify family and find relatives who could care for the baby, Elliot says.