In this representational image, a stand-up paddle boarder heads out into the waves near the cliffs of La Jolla, California, Jan. 20, 2016. REUTERS/Mike Blake

Authorities in Northern California said Wednesday they believe all six children from a family of eight are dead, after an SUV plummeted off a coastal cliff on Monday. Their parents also died in the crash. Mendocino County Sheriff Tom Allmon told reporters on Wednesday only bodies of three children were recovered.

"We have every indication to believe that all six children were in there," Sheriff Allmon said, requesting for tips to retrace where the children and their parents had been before the vehicle was discovered on Monday on the rocky ocean shore. "We know that an entire family vanished and perished during this tragedy."

Crews earlier put the death toll at three children and said three were missing. The SUV reportedly plunged 100 feet from an ocean overlook on the Pacific Coast Highway, about 150 miles north of San Francisco on Monday, authorities said.

The California Highway Patrol claimed it is unclear what caused the SUV to drop off the cliff and have not determined the exact cause yet. Authorities said a specialized team of crash investigators are studying the scene for clues.

"There were no skid marks, there were no brake marks" at the turnout on the Pacific Coast Highway where the SUV went over, the sheriff said.

According to CBS affiliate KOIN-TV, the children who were first said to be missing and whose bodies have not yet been discovered are 15-year-old Devonte, 16-year-old Hannah and 12-year-old Sierra Hart.

Nineteen-year-old Markis, 14-year-old Jeremiah and 14-year-old Abigal Hart were confirmed dead on Wednesday.

California cliff
In this representational photo, apartments are seen at the edge of an eroding cliff in Pacifica, California, Jan. 27, 2016. JOSH EDELSON/AFP/Getty Images

California Highway Patrol previously stated the family was from West Linn, Oregon, however they recently lived in Woodland, Washington, Clark County sheriff's Sgt. Brent Waddell said. Parent Jennifer Hart was said to be driving at the time of the crash, according to Fox News.

One of the children, Devonte came into the spotlight after he was photographed at a 2014 protest in Portland, Oregon, following a grand jury's decision not to indict a police officer in the fatal shooting of a black man in Ferguson, Missouri.

Devonte, who is black, was holding a sign that read "Free Hugs," when a white officer asked him if he could get one. The photo that went viral showed an emotional Devonte embracing the officer.

At the time, Jennifer wrote on social media: "My son has a heart of gold, compassion beyond anything I've ever experienced, yet struggles with living fearlessly when it comes to the police. ... He wonders if someday when he no longer wears a 'Free Hugs' sign around his neck, when he's a full-grown black male, if his life will be in danger for simply being."

Authorities said there was nothing, at this point, to indicate the crash was intentional.

Allmon added that a witness called 911 about the incident. However it was not clear when exactly the SUV plunged over the ledge.

Investigators said that the appearances at the family's home suggested the Harts were on a short road trip, as they left behind several personal belongings including their chickens and a pet.