A 25-year-old east Georgia police officer hit another vehicle head-on and died Saturday, also killing the other driver.

Auburn police Officer Jacob Peek was off-duty when his Ford Mustang drifted into oncoming traffic on Carl-Midway Church Road in Barrow County, according to the Georgia State Patrol. It crashed into a southbound Toyota Corolla driven by Zachary Smith, 28, of Auburn.

Both men were dead when the GSP responded to the crash scene shortly after midnight Saturday. Three passengers in Peek’s Mustang and one passenger in Smith’s Corolla were taken to Gwinnett Medical Center with serious injuries, GSP spokesman Lt. Mark Riley said.

Updates on their conditions were not provided Tuesday.

Investigators do not know why Peek “lost control” and traveled into the southbound lane, and the crash remains under investigation, Riley said.

Prior to accepting the job at the Auburn Police Department, Peek served as an officer with the city of Winder. A memorial service is set for 4 p.m. Saturday in the chapel of the Smith Funeral Home in Winder.

Smith’s funeral is scheduled for 2 p.m. Friday in the chapel of Flanigan Funeral Home in Buford. He leaves behind a wife and 5-year-old daughter.