An active-duty soldier stationed at Fort Benning, Ga. is facing a reckless murder charge after reportedly making his girlfriend’s five-year-old son get out of their vehicle because he was “being unruly,” leading to him being struck and killed by another vehicle on a highway.

Sgt. 1st Class Bryan Starr, 35, was driving around 8 p.m. on Sunday when the boy, identified as Austin Birdseye, began acting “unruly” in the vehicle, according to WRBL, a CBS-affiliate in Columbus. Starr reportedly pulled over at a church and told Birdseye to get out of the car while it was raining.

He “lost track of the boy in the rain,” per WRBL, who “wandered onto the busy highway and was struck by another vehicle.” Birdseye later died at Piedmont Columbus Regional. His mother was not in the car at the time.

Ben Garrett, spokesman for Fort Benning, confirmed that Starr “turned himself into the Russell County, Alabama, sheriff’s office regarding the tragic death of a 5-year-old boy in his care.”

“We are deeply saddened by this tragic event and extend our heartfelt condolences to the family of the deceased,” Garrett said.

Starr, from Marengo, Ill., is assigned to the 3rd Squadron, 16th Cavalry Regiment, 316th Cavalry Brigade. He has completed 17 years of service and one combat deployment to Iraq.

According to WRBL, investigators are still working to determine how long the little boy was outside the car before he was hit. The two were “just a few miles away” from the home Starr and Birdseye’s mother share.

Russell County Sheriff Heath Taylor called the incident “horrific.”

“I can’t imagine the mother’s grief that she is going through. It’s just tough,” Taylor said according to WRBL. “What do you say to that? What is your thought process when you tell a five-year-old to get out of the car on a rainy night because they were loud in the car? It’s just heartbreaking.”