CENTREVILLE, Va. (AP) — A bus driver for an elementary school in the nation’s capital has been charged with driving while intoxicated after his bus veered into a ditch while returning from a field trip to a farm in northern Virginia.

Nine children were treated at the scene for minor injuries, Fairfax County Police said.

The bus was carrying 44 children and four adults back Thursday to Murch Elementary School in Washington, D.C., after a field trip to Cox Farms in Centreville, Virginia — a popular field trip destination in the region.

Police said the bus hit a rock and veered into a ditch off a road in the northern Virginia county.

The 48-year-old driver from Suitland, Maryland, was charged after police say he failed a field sobriety test and had a blood-alcohol content of .20, more than double the legal limit of .08.

Police say the driver’s license had already been revoked in Virginia from a prior drunken driving conviction.

Officers also said they found a combined 18 safety violations on the two buses carrying children to the field trip and that none of the operators were properly licensed to operate a school bus.

D.C. Public Schools said in a statement that it plans to undertake a review of the transportation vendors it uses for field trips and other extracurricular activities.