Tragedy struck Northwestern Minnesota city of Moorhead Saturday night when concerned family members checked a house, and found the deceased bodies of four adults and three children inside.

The City of Moorhead Police Department is currently investigating, and they confirmed the “unattended deaths” in a short statement on Sunday night. They noted that there were no visible signs of violence or forced entry discovered at the crime scene.

The bodies will be taken to the Ramsey County Medical Examiner’s office for autopsies. The Moorhead PD has reportedly reached out to the Minnesota Bureau of Criminal Apprehension Crime Scene Team for assistance in the investigation, though they also confirm that there is currently no known threat to the public. Investigators now believe that carbon monoxide poisoning caused the deaths.

Moorhead’s Mayor Shelly Carson mourned the losses in a statement shared with The Star Tribune. “This is an absolute horrible tragedy, made even more poignant since it is close to the holidays,” said Carson.

Neighbors last saw the children on Friday.

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