OMAHA, Neb. (AP) — An Omaha man was found dead and his sister was hospitalized after Omaha firefighters responded to a report of carbon monoxide poisoning.

The Douglas County Sheriff’s Department says 74-year-old Terry Hart was found dead in an Omaha home Friday afternoon and his sister, 72-year-old Joyce Porter, was found in critical condition in the basement. She was taken to the Nebraska Medical Center.

Investigators say a car was accidentally left running in the garage overnight. Hart was found in the bedroom above the garage.

Relatives called 911 around 2:20 p.m. Friday after Hart and Porter didn’t show up to meet family members for lunch.

An autopsy is scheduled for Saturday.