The three young US Marines who were found dead in a car at a gas station near Camp Lejeune in North Carolina died from carbon monoxide poisoning, authorities said.

Officials also revealed that the missing-person call that led to the tragic discovery on Sunday morning came from the worried mom of one of the dead servicemen, the Jacksonville, North Carolina, Daily News said.

The Pender County Sheriff’s Office got the call shortly before 8:30 a.m., with the woman reporting that her Marine son never showed up on his scheduled flight home to Oklahoma the night before, the outlet reported.

The sheriff’s office later found the three in a four-door sedan in the parking lot of a Speedway Convenience Store in Hampstead — all dead.

Authorities did not immediately say whether the deaths were believed to be accidental.

The three, all with the rank of lance corporal, were identified as Merax Dockery, 23, of Pottawatomie, Okla., Tanner Kaltenberg, 19, of Madison, Wis., and Ivan Garcia, 23, of Naples, Fla.

In a statement Tuesday, the US Marine Corps said all three were pronounced dead “by a competent medical authority” and the case is under investigation by the sheriff’s office.

“[The] 2nd Marine Logistics Group will continue to support NCIS and local authorities in
the conduct of their investigation,” the statement said, referring to the Naval Criminal Investigative Service.

Group commander Brig. Gen. Michael McWilliams expressed his “deepest sympathy and condolences … to the family, friends, and colleagues” of the dead Marines.

“Our focus is providing the necessary resources and support to those impacted by their tragic loss as they navigate this extremely difficult time.”