Two girls, ages 12 and 8, reporting missing Monday from their foster home, along with their foster parents' car, were found Tuesday in Oklahoma.

Authorities believe the pair may have been abducted, and are seeking the biological mother of one of the young girls.

San Dimas, Calif., sheriffs were calling the mother of 12-year-old Estephanie Flores a "person of interest" in the children's disappearance, deputies told FOX News.

Estephanie's mother, 38-year-old Iris Pineda Zavala of Monrovia, is being urged to call police.

Los Angeles County Sheriff's Lt. Roxanna Hart said the girls were reported missing shortly before 7 a.m. Monday, along with the family's 1998 Lexus.

Estephanie has been in the foster home for 5 months, while Robin has only been in the home for a month.

Lemus' biological father, Felico Lemus, told MyFOX Los Angeles that the girls might have been mistreated by their foster parents.

"In a text message, she said, 'Dad my foster parents are really mean,'" Lemus said. "She said, 'I want my true parents back.'"

The foster parents first believed the two were out "joyriding in the family vehicle," according to Hart.

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The Associated Press contributed to this report.