California investigators believe they have determined what caused a young family to die on a hiking trail in mid-August.

The investigators discovered the hikers, John Gerrish, his wife Ellen Chung, their 1-year-old daughter, Miju, and pet dog, Oski, only carried a total of 84 ounces on their hike in the Sierra National Forest. The water amount was far short of the 320 ounces recommended for hiking the trail they were on, which can reach up to 109 degrees during the summer. A survival trainer believed the family was "caught off guard" by their circumstances, according to the San Francisco Chronicle.

“It is likely the child began to succumb first, which hurried the parents’ efforts up the hill," the trainer told investigators. "When one could no longer continue, they stayed behind to care for the child and pet, while the other tried to forge on and get help for their loved ones. It is a tragedy of the highest order.”

CHEF SENTENCED AFTER UNDERCOOKED MEAL LED TO ONE DEATH, 30 CASES OF FOOD POISONING

The family took their hike on Aug. 15, with a search beginning the following day. Investigators found the bodies of Gerrish, his child, and the dog first, with Chung’s body about 13 feet in elevation higher than the others. Inside Chung's 2.5-liter Osprey Hydraulics LT water bladder were only a “few remaining drops” of water, which detectives found no toxins in, according to the outlet.

Mariposa County Sheriff Jeremy Briese closed the case in October, blaming hyperthermia and probable dehydration as the reasons for Gerrish, Chung, and their daughter's deaths. Briese said the family got too hot, causing their brains and organs to shut down, and called the situation "an unfortunate and tragic event due to the weather,” the outlet reported.

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Authorities initially considered toxic algae blooms in nearby water to be responsible for the family's death. The Sierra National Forest warned about the algae on Facebook in July and asked visitors not to swim, wade, or let their pets play in the water.