The three U.S. Marines who were found unresponsive at a Speedway gas station in North Carolina near Camp Lejeune died of carbon monoxide poisoning, officials said Wednesday.

Deputies from the Pender County Sheriff's Office found the three men in a privately owned car outside the convenience store Sunday morning. 

Camp Lejeune

Signage stands on the main gate to Camp Lejeune Marine Base outside Jacksonville, N.C., on April 29, 2022. (AP Photo/Allen G. Breed)

The lance corporals, identified by the U.S. Marine Corps as Tanner J. Kaltenberg, 19, of Madison, Wisconsin; Merax C. Dockery, 23, of Pottawatomie, Oklahoma; and Ivan R. Garcia, 23, of Naples, Florida, were stationed at nearby Camp Lejeune. 

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Autopsies performed Wednesday by the North Carolina Office of Medical Examiner determined that all three deaths were the result of carbon monoxide poisoning, according to the sheriff's office.

The Pender County Sheriff's Office did not immediately make clear whether their deaths were accidental.

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"I am saddened by the timeless and tragic death of these three young men, who served our country honorably," Sheriff Alan Cutler said. "Our thoughts and prayers remain with their families and colleagues during this time."

The Associated Press contributed to this report.