Authorities continue to search for three children Thursday who are unaccounted for after their siblings and parents plunged off a cliff in Mendocino County. 

Neighbors of Hart family speak

They’re using boats, aircraft and drones to look for 16-year-old Hannah Hart, 15-year-old Devonte Hart and 12-year-old Sierra Hart.

The drone video shows the crash side where 19-year-old Markis Hart, 14-year-old Jeremiah Hart and 14-year-old Abigail Hart died along with their parents, Jennifer and Sarah Hart.

Their SUV plunged 100 feet from the Pacific Coast Highway onto rocks in the ocean Monday.

Highway Patrol says the couple’s three other children haven’t been found and searchers are scouring the region.

“There are a lot of unknowns on this,” Mendocino County Sheriff Tom Allman said. “Several of the questions that have been asked today will never be answered.”

Investigators have yet to determine the cause of the crash and said there is no reason so far to believe it was intentional. But they also said there were no skid marks or signs the driver braked as the GMC Yukon crossed a flat dirt pull-off area, about 75 feet wide, and went over the edge of the Pacific Coast Highway.

KRON4’s Gabe Slate was at the site of the crash Thursday as investigators continue to search.Slate says there were nine volunteers of the Mendocino Sheriff Search and Rescue team out looking for the three missing teens. 

They were using high powered spotting scopes to comb the beach and ocean from above on the cliffs.

Crews started at the Juan Creek turn around crash site and are moving south. 

Search crews are using dogs to help in their search.