HIGHLAND PARK, Ill. (AP) — Authorities believe a Highland Park couple found dead in their home were poisoned by carbon monoxide from a car with keyless ignition after it was accidentally left running in the garage.

The bodies of 79-year-old Pasquale Fontanini and his 76-year-old wife, Rina, were discovered by their son early Monday morning. They were pronounced dead at the scene.

Cesare Fontanini, a Highland Park Fire Department lieutenant, says it appears his parents’ car was inadvertently left running. He says the fire department detected high levels of carbon monoxide when first responders arrived at the home.

The Chicago Tribune reports that several other deaths nationwide have been attributed to cars with keyless ignitions.

A Highland Park police official says the department has discovered cars with keyless ignitions running unattended in Ravinia parking lots.