YUMA, Ariz. (AP) -- School officials in San Luis, Ariz., are investigating a busing mix-up that ended with a 6-year-old boy wandering alone in Mexico.

Gadsden Elementary School District board President Luis Marquez says that if any failure is found in the school transportation system, it will be corrected immediately.

The boy was headed home last week when he boarded a school bus with a different route than the one he usually takes.

The boy's mother said her son was disoriented when he got off and crossed into San Luis Rio Colorado, Mexico. She says her son thought he could reach his grandfather's home in Mexico.

The 6-year-old was returned home safely after being found by a passer-by in Mexico.