Petty Officer Third Class Gene Clayton, 22, of Poland, Ohio, was taken off life support at Scripps Memorial Hospital early on Saturday, a spokeswoman for the hospital said.
"Apparently he was out for the evening and he had gone home with a young lady and was handling a firearm and accidentally shot himself in the head," said Allen Sluss, a watch commander for the San Diego Police Department.
"It was deemed accidental, it wasn't an intentional act."
Police said the woman told Clayton to put the guns away and Clayton, as if to demonstrate they were safe, put a pistol to his head and pulled the trigger. Police said Clayton may have thought the gun was unloaded.
Paramedics carried Clayton early on Thursday to the hospital where he was placed on life support.
Clayton had recently completed SEAL training. He is survived by his parents and three sisters, police said.
(Reporting by Eric Johnson in Chicago; Editing by Ian Simpson)
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