RYE BROOK, N.Y. (CBSNewYork) — An 85-year-old man and his step-grandson were found dead in their home late Monday, and police say carbon monoxide poisoning was to blame.

As CBS2’s Tracee Carrasco reported, the Westchester County Medical Examiner’s office and an ambulance remained on scene in front of the home on Maywood Avenue in Rye Brook as of 5 p.m.

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Police said Carl Persson, 85, and his step-grandson Joseph Pendrak, 50, were found dead in their bedrooms in the house likely from carbon monoxide poisoning.

Police said it appears a car was accidentally left on in the attached garage, and the carbon monoxide drifted into the house.

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Family members said the last time the men were seen alive was on Saturday, but their bodies were found around noon Monday after families could not reach them.

“Upon officers’ arrival, they found two people who were deceased. Both were in bed in separate bedrooms. The investigation revealed that it was a possible carbon monoxide poisoning – the source being a car that was found in the garage that had the ignition on, was out of gas, and we believe that the fumes from the car possibly, or most likely, drifted into the house – causing both people to suffocate,” said Rye Brook police Chief Gregory Austin.

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Police late Monday were not sure why the car was accidentally left on. They said there were no carbon monoxide detectors in the home.