WESTPORT, Calif. – The remains of a human foot were found inside a shoe along the California coast, about one mile north of the Hart family crash site, authorities said Thursday.

A local resident found the shoe tangled in a pair of blue jeans on the beach Wednesday night, according to the Mendocino County Sheriff's Office.

The jeans were a girl’s size 10 regular, and the shoe was a kids’ size 3.5 and/or a women’s size 5.5.

The skeletal remains were sent to the Mendocino County Sheriff's Office coroner.

The Hart family’s SUV was found March 26 at the base of a cliff on the California coast. The bodies of Sarah, Jennifer and four children: Markis, 19, Jeremiah, 14, Abigail, 14, and Ciera, 12, have been found.

Two children, Devonte, 15, and Hannah, 16, are missing and presumed dead.

The sheriff's office did not confirm whether the remains belong to one of the missing children. They will be tested through DNA analysis.

On Thursday, authorities also revealed that three children tested positive for Diphenhydramine -- the active ingredient in Benadryl -- as did Sarah Hart. The drug is often used as a sleep aid.

One child had no toxicology finding, the sheriff's office said. Authorities did not say which children tested positive for the drug.

What we know: Hart family crash

Mendocino County Sheriff's Office Search & Rescue members on Thursday were deployed to the area where the remains were found. They will search the area during low tide, and assess the area to plan a future search.

The news comes several weeks after the latest update in this tragic case. In April, Oregon's Department of Human Services revealed the agency knew of child welfare concerns in Oregon and Minnesota, where the Hart family previously lived. Despite knowing of reports of neglect, DHS determined there was not enough evidence to continue an investigation into the family in 2013.

Oregon DHS knew of other abuse allegations involving Hart family

The Harts moved to Woodland, Wash. in 2017. DHS officials there were again alerted to concerns of neglect. The day Washington Child Protective Services visited the family to check in, Jennifer and Sarah Hart left with their six children on a trip to California. Three days later, the family's crashed SUV was found.

Timeline of Hart family’s child welfare concerns in WA, OR, MN