Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

Devonte Hart first grabbed attention in the "hug felt 'round the world."

The black youth, with tears streaming down his face, was captured in a viral photo in November 2014 clinging to the shoulders of a white police officer at a protest in Portland, Oregon, a few months after the police shooting of an unarmed black teenager in Ferguson, Missouri.

It became an emblematic moment during national rallies that rocked the country after a grand jury chose not to indict a white police officer in the killing of Michael Brown, 18.

But now, police in Northern California say Devonte and his family are at the center of a mysterious crash, and they need the public's help.

Devonte, 15, and two of his sisters remained missing Thursday — three days after the SUV they were riding in with their parents and three other siblings plunged off a cliff on Highway 1 in Mendocino County, police said.

A passer-by reported seeing the 2003 GMC SUV upside down off an embankment. Police said the car fell about 100 feet, landing on the rugged shoreline along the Pacific Ocean.

The pullout where the SUV of Jennifer and Sarah Hart was recovered off the Pacific Coast Highway, near Westport, California, on Wednesday. Alvin Jornada / The Press Democrat, via AP

The Mendocino County Sheriff's Office has retrieved the bodies of Devonte's parents, Jennifer and Sarah Hart, both 38, as well as his siblings Markis, 19, Jeremiah, 14, and Abigail, 14.

Devonte and two other sisters — Hannah, 16, and Sierra, 12 — have not been located, but were believed to have been inside the SUV.

A special team of accident investigators is trying to figure out why the car flew off a dirt turnout in a part of the cliffside where many tourists stop for photos, Sheriff Tom Allman said Wednesday.

"We have no evidence and no reason to believe that this was an intentional act," he said. But he noted that the scene was confusing because "there were no skid marks, there were no brake marks" at the turnout.

The Morning Rundown Get a head start on the morning's top stories. This site is protected by recaptcha

Investigators said the U.S. Coast Guard along with a helicopter and small plane were helping to search for Devonte, Hannah and Sierra.

The family was from Woodland, Washington, a rural community about 500 miles north of the accident site, and it was unclear why they were traveling in California. Police in Clark County, Washington, said they had entered the Hart home and determined that no one was still there.

"It appeared the family may have left for a temporary trip as there were many family belongings still in the home as well as a pet and some chickens," the Mendocino County Sheriff's Office said, citing the Clark County officers.

Zippy Lomax, a friend of the family since 2012, told The Oregonian that the Harts loved to travel and were always "going somewhere special."

"They weren't plugged into the technology," she said. "They preferred to lay (around) and read books and hang out with their chickens."

Devonte Hart with his family in Astoria, Oregon, in 2014. Thomas Boyd / The Oregonian, via AP

The family called themselves the Hart Tribe, and Jennifer and Sarah home-schooled the children, who were all adopted. A next-door neighbor of the Harts when they lived in Oregon told The Associated Press that they didn't eat sugar, grew their own vegetables and liked to go on camping trips.

The parents also didn't shy away from having the siblings learn about social justice and experience events firsthand, including the rally in Portland that Devonte attended.

The boy was holding a "Free Hugs" sign when an officer, Sgt. Bret Barnum, asked him for a hug, and a photographer snapped the emotional moment.

Jennifer Hart later posted on Facebook that Devonte had his own questions about police racism: "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," she wrote. "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."

Barnum said in a statement Thursday that what happened to the family "deeply saddens me," and meeting Devonte has been "one of those moments in my career which reinforced my love, passion, and duty in providing compassion and service to my community."

In recent months, after the family moved to Woodland, neighbors said that not everything seemed quiet and peaceful.

Neighbors told The Oregonian that Devonte would come asking for food and said his parents withheld it as punishment.

A former neighbor, Bill Groener, said he was struck by how isolated the kids were kept, and told The Oregonian that he felt guilty for neglecting to call child welfare authorities.

While living in Minnesota in 2011, Sarah Hart pleaded guilty to a misdemeanor domestic assault charge in connection to one of the daughters, Abigail, court records show. The girl, then 6, told a teacher that she had "owies" on her body and "Mom hit me," the complaint said.

Hart served a year's probation without incident, according to Douglas County court records. She told police that they normally don't use spanking as a disciplinary measure but had been using it to deal with the girl's behavior, and told police she let her anger get out of control, according to a police report.

Norah West, a spokeswoman for the Washington Department of Social and Health Services, said the family had no prior history with child protective services in the state, but an inquiry was recently opened to investigate possible abuse or neglect.

A representative in Cowlitz County tried to visit the family's home Friday, but no one answered the door, she added.

It's unclear when exactly the family set off on their road trip.

Lomax told The Oregonian that there was no sign that anything was amiss all these years. To her, the trek to California was probably just another one of their adventures.

The Harts "loved their kids more than anything else," she said.