A family that gained attention 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 Wednesday as they asked for help figuring out what happened.



"We have every indication to believe that all six children were in there," Mendocino County Sheriff Tom Allmon said, appealing for tips to retrace where the siblings and two parents had been before the vehicle was found Monday in rocky ocean. "We know that an entire family vanished and perished during this tragedy."



Some friends described married couple Jennifer and Sarah Hart as good parents who took their adopted kids to Bernie Sanders rallies, while some neighbors 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 specialized team of accident investigators was trying to figure that out, Allmon 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 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 Harts lived in Woodland, Washington, a small city outside Portland, Oregon, and had a recent visit from Child Protective Services, Clark County sheriff's Sgt. 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 neighbors 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.