A family of eight who gained attention in the US for an emotional photograph of an African-American boy hugging a white police officer at a 2014 protest were killed when their SUV plunged off a scenic California highway, authorities said.
"We have every indication to believe that all six children were in there," Mendocino County Sheriff Tom Allman said, appealing for tips to retrace where the siblings and two parents had been before the vehicle was found on Monday in rocky ocean.
"We know that an entire family vanished and perished during this tragedy," he added.
Some friends described married couple Jennifer and Sarah Hart as loving parents who took their adopted kids to Bernie Sanders rallies, while neighbours said they called child welfare officials in their rural Washington state community over concerns about possible abuse or had noticed red flags.
The California Highway Patrol has not determined why the vehicle went off an ocean overlook on a rugged part of coastline.
A specialised team of accident investigators was trying to figure that out, Mr Allman said.
"There were no skid marks, there were no brake marks" at the turnout on the Pacific Coast Highway where the vehicle went over, the sheriff said.
Investigators have no reason to believe the crash was intentional, he said.
The 100-foot (31m) drop killed the women, both 39, and their children Markis Hart, 19; Jeremiah Hart, 14; and Abigail Hart, 14. Hannah Hart, 16; Devonte Hart, 15; and Sierra Hart, 12, have not been found.
The family got attention after Devonte Hart was photographed during a 2014 protest in Portland, Oregon, over a grand jury's decision not to indict a police officer in the shooting of a black man in Ferguson, Missouri.
The boy, holding a "Free Hugs" sign, stood crying. A Portland officer saw his sign and asked if he could have a hug, and an emotional Devonte embraced him in a picture that was widely shared.
At the time, Jennifer Hart 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."
The family travelled to many festivals throughout the area - including events for presidential candidate Bernie Sanders - and were known for wearing matching T-shirts.
The Harts lived in Woodland, Washington, a small city outside Portland, Oregon, and had a recent visit from Child Protective Services, Clark County sheriff's Sergeant Brent Waddell told The Associated Press.
He said the sheriff's office later entered the house and found no obvious signs of trouble or violence. It appeared the family planned a short trip because they left behind a pet, chickens and most of their belongings.
Next-door neighbours Bruce and Dana DeKalb said they called child services Friday because they were concerned that Devonte Hart, who hugged the officer at the protest, was going hungry.
They said he had been coming over to their house too often in the past week asking for food.
They also recounted that three months after the family moved into the home on two acres with a fenced pasture in May 2017, one of the girls rang their doorbell at 1.30am.
She "was at our door in a blanket saying we needed to protect her," Bruce DeKalb said. "She said that they were abusing her. It haunted my wife since that day."
In 2011, Sarah Hart pleaded guilty to a domestic assault charge in Minnesota. Her plea led to the dismissal of a charge of malicious punishment of a child, online court records say.