ALTA, Calif., KCRA — Placer County sheriff’s deputies are investigating an apparent carbon monoxide death.

Sheriff’s deputies say two men were sleeping inside the camper of a pickup truck, which was parked inside a garage on their friend’s property in the town of Alta.

The landowner says he discovered the men just before midnight. He said a 56-year-old man was dead and his 46-year-old friend was unconscious.

The unconscious man was taken to a hospital in Fairfield and put into an hyperbaric chamber, according to officials.