A French couple died while hiking across the New Mexico desert in scorching heat. Their 9-year-old son survived and was found by deputies Tuesday.

Otero County Sheriff Benny House told reporters Friday that the boy was spotted beside his father, who was already dead at the time, along the Alkali Flat Trail at the White Sands National Monument. He was found about half-hour after his mother was discovered, also dead, on the trail going back to the car, CNN reports.

The couple died of heat-related causes, authorities said, according to CNN.

The sheriff identified them as David Steiner, 42, and wife Ornella Steiner, 51. They were from the town of Bourgogne, France, Fox News reports.

The three reportedly went for a hike Tuesday afternoon when, about a mile-and-a-half down the trail, Ornella reinjured her previously hurt knee and decided to head back to the car. She collapsed along the way after walking for just about 300 feet.

David and his son, not knowing about what happened to Ornella, continued their hike. After a while, David became disoriented and delirious as the heat started to overcome him.

"He kept telling the son that the vehicle is 'right over here, right over here,'" House said, CNN reports.

Meanwhile, park troopers saw Ornella lying dead on the ground. Wondering why she was hiking alone, the troopers looked at her camera and saw photos of David and the boy. After learning that the two were unaccounted for, the troopers alerted the sheriff's office and a search was conducted.

David and his son were found about 30 minutes after park troopers found Ornella, but David was already dead.

Authorities said the three were carrying two 20-ounce water bottles for the hike. David and Ornella would take one sip but would give their son two sips of water each time they stopped to drink. Authorities said this - and the fact that he was younger - may be the reason the boy survived, according to The Guardian.

The sheriff's office informed the French consulate about the tourist couple, and the boy's relatives were contacted. On Thursday, the boy's grandmother went to Albuquerque to bring him home, according to The Guardian.