GREENVILLE, S.C. -- Authorities say a Greenville couple has died after a car was left running at their house earlier this month.

Deputy Coroner Jeff Fowler said Tuesday that 76-year-old William Thomason and 71-year-old Woo Thomason both died from a brain injury caused by carbon monoxide poisoning.

Police spokesman Lt. Jason Rampey says officers found the couple unconscious in their home on June 9 after friends reported them missing. The Thomasons died at the hospital days later.

Rampey said the battery on one of the cars in the couple’s basement garage was dead, and its fuel tank was empty.

Investigators think one of the Thomasons went to the store, drove into the garage and accidentally left the car running. Authorities say fumes got into the house through the heating and air system.