APPLE VALLEY, Calif. — A school bus driver here was arrested for allegedly leaving a preschool student with special needs alone on a bus for an hour.

On Aug. 23, the student was discovered to have been left on a bus at the end of the school day, according to a news release from Apple Valley Unified School District.

Another bus driver discovered the student, who was unharmed, approximately an hour after the bus route had ended. The child’s parents were immediately contacted and she was taken home. She is now back in school and using district transportation, according to the news release.

District officials said that they immediately contacted the San Bernardino County Sheriff’s Department and cooperated with an investigation into the incident. Full details were being determined pending the investigation.

A refresher training course was held the morning after the incident to reiterate the district’s transportation procedures, and further measures have been put into place to ensure that this does not happen again, according to the district.

“Words cannot express how dismayed we are that this occurred and how seriously we are taking this incident,” the news release stated. “The safety of our students is our top priority.”

The bus driver, Tiffeny Beatrice Avery, has been placed on administrative leave. She has been charged with one count of felony child abuse, according to NBC4.

The bus that the student was riding was dedicated to transporting special-needs students, and it was unclear why the student had not been taken to her home as all the other students were, according to the news source.

The incident occurred less than one year after a student with autism died after being left unattended on a school bus for several hours in Whittier, less than 90 miles away. The death of  Hun Joon (Paul) Lee spurred a bill, SB 1072, also known as the “Paul Lee School Bus Safety Law,” that would require school buses in the state to be equipped with child-check alarm systems. Gov. Jerry Brown has until Sept. 30 to take action on the bill.