BELTSVILLE, Md. — A school bus driver was arrested on Monday morning after his bus rolled into a small child.

According to the Prince George’s County Police Department, a preliminary investigation of the incident revealed that there were four students on the bus but no driver. Investigators said they believe the driver had parked the bus near a high school and briefly left it unattended.

The bus rolled across the road, struck a boy who was standing on a corner, and then came to rest. Prince George’s police said it was not yet known why the bus rolled across the road.

A Baltimore County auxiliary police officer who witnessed the accident rushed to the scene to help. He pulled the boy from underneath the bus and stayed with him until paramedics arrived and transported the boy to the hospital.

The four students who were on the bus were also transported to the hospital with minor injuries.

Prince George’s police said later in the day that all five children had been released from the hospital.

Police arrested 61-year-old Arturo Roberto Harris, a Prince George’s County Public Schools bus driver. Harris faces multiple charges related to the incident, including reckless endangerment, leaving a child unattended and several traffic offenses.