A Forsyth, Georgia, man and his infant son were found dead inside a car over the weekend, in a Waffle House parking lot.

According to the Butts County Sheriff’s Office, Christopher Gage McKinzie, 26, and 10-month-old Sawyer Gage McKinzie are believed to have succumbed to carbon monoxide poisoning. The man’s girlfriend was also found in the car and was taken to a local hospital for treatment, while McKinzie and his son were pronounced dead on the scene.

Police responded to the scene early on Nov. 14 after receiving reports of several people found unresponsive in a vehicle in the restaurant’s parking lot, on Ga. Highway 36 at I-75.

According to co-workers, as reported by Clayton News Daily, McKinzie got off work at the Waffle House at 12:30 a.m. and went to sleep in the car with his son with the engine running, waiting for his girlfriend to get off from work at 2:30 a.m. Went she got off, she also got into the car and went to sleep.

According to family, Christopher McKinzie graduated from Mary Persons High School in 2013 and had worked for Waffle House for the past 10 years.