A family of three who had been reported missing have been found dead, along with their dog, in Sierra National Forest.

As KSEE and CBS News report, a friend filed a missing persons report Monday for John Gerrish, Ellen Chung, their 1-year-old daughter, Muji. The circumstance of their disappearance remains unclear. It is not known how long they were gone and police have not yet confirmed that the family was on a planned hike or camping trip.

While searching for the family, who was traveling with their dog, police first discovered their vehicle near an entrance to the Sierra National Forest, KTLA reports. Investigators then found the bodies of all three family members and their dog in the remove Devil’s Gulch are near the Merced River. According to multiple local reports, there was no visible signs of trauma and investigating agencies, including the California Department of Justice, are treating the area as a hazmat scene.

“It could be a carbon monoxide situation,” Mariposa County Sheriff’s Office spokesperson Kristie Mitchell told CBS News.

This is a developing story. CrimeOnline will provide further updates when more information is available.

For the latest true crime and justice news, subscribe to the ‘Crime Stories with Nancy Grace’ podcast. Listen to the latest episode:

[Feature image: Provided to KSEE by Rosann Heaslett]