A California family of three that had been reported missing this week was found dead Tuesday along with their dog in a remote area of the Sierra National Forest, according to authorities. 

The family was reported missing by a friend Monday night and search teams located their vehicle near a Sierra National Forest gate leading to Hites Cove in California. 

John Gerrish, Ellen Chung, 1-year-old daughter Miju, and their family dog were later found dead near an area known as Devil’s Gulch in the Southfork of the Merced River drainage, according to the Mariposa County Sheriff's Office.

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"This is never the outcome we want or the news we want to deliver, my heart breaks for their family," said Sheriff Jeremy Briese. "Our Sheriff’s Chaplains and staff are working with their family and will continue to support them during this heartbreaking time."

Kristie Mitchell, a spokeswoman with the sheriff’s office said there were mines in the area and no clear cause of death, leading authorities to treat the area as a hazmat scene for the safety of those responding, according to The Fresno Bee. An investigation to determine the cause of the family’s death is underway.

"Coming across a scene where everyone involved, including the family dog that is deceased, that is not a typical thing that we have seen or other agencies have seen," Mitchell told the Bee. "That is why we’re treating it as a hazmat situation. We just don’t know."

"It could be a carbon monoxide situation. That’s one of the reasons why we’re treating it as a hazmat situation," Mitchell added. 

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The bodies were found in a remote area with no cell phone service, Mitchell noted. The area was located near the Hite Cove trail -- known for having striking wildflower displays in the spring. 

Sierra National Forest (U.S Department of Agriculture, Forest Service)

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The sheriff's office is conducting an investigation into the deaths with the assistance of the California Department of Justice. 

The Associated Press contributed to this report