SONORA (AP) — Police in Sonora are trying to determine how three third-graders caught smoking marijuana got the drug.

Sonora Police Chief Mark Stinson says the two 8-year-olds and a 9-year-old were discovered by another student last week at Sonora Elementary School. Superintendent Leigh Shampain told KPIX-TV the students were smoking in a school bathroom.

The student who found the smokers told school officials, who contacted police.

The third-graders were released to their parents.

Stinson said on Wednesday police were looking into whether someone supplied the drug to the kids.

Shampain would not discuss how the third-graders might be disciplined.