UPPER MARLBORO, Md. — A former school bus driver whose unattended bus rolled into a small child in April pleaded guilty to reckless endangerment and other charges, authorities said on Monday.

In the April 7 incident, investigators found that 61-year-old Arturo Harris, then a Prince George’s County Public Schools bus driver, left four students unattended on his bus while he went into a high school to use the restroom.

The bus rolled down a hill and across the road toward children waiting at an elementary school bus stop. The driverless vehicle then struck a 6-year-old boy and came to rest.

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. The Prince George’s County Police Department said later in the day that all five children had been released from the hospital.

Police arrested Harris on multiple charges.

On Monday, Prince George’s County State’s Attorney Angela Alsobrooks announced that Harris pleaded guilty to one count of leaving an unattended child, three counts of reckless endangerment and one count of failing to curb the wheels of an unattended vehicle.

Alsobrooks said in a statement that Harris “exercised poor judgment by leaving those children alone on an unsecured bus.”

“Thankfully the children on the bus were not harmed, and the child who was struck sustained only minor injuries,” Alsobrooks said.

She added that the case “sends a message that this type of negligent behavior will not be tolerated, and certainly Mr. Harris should never be allowed to drive a school bus again.”

Prosecutors are asking that Harris be sentenced to 15 years, suspend all but 30 days — which can be served on weekends — and three years of supervised probation. His sentencing is scheduled for Nov. 7.