CARLSBAD, Calif. (KABC) -- The California Highway Patrol says it stopped a car and found a teen bound and gagged by family members, so they could take her to a drug rehabilitation center in Mexico.The stop was made on Interstate 5 in the city of Carlsbad in San Diego County.The officer spotted the 17-year-old girl in the backseat, tied up with a gag in her mouth.According to the CHP, the teen admitted to using methamphetamine for the past year, and her father and 21-year-old sister had forced her into the car to take her to a treatment center in Mexico.The teen was taken into protective custody.No charges have been filed, but the case is under investigation.