UNIONTOWN, Pa. — State police have charged a southwestern Pennsylvania high school student with emptying a liquid in a school bus that caused three other students to suffer headaches, eye irritation and nausea.

Troopers from the Uniontown barracks have not said what substance was dumped on the bus Monday morning in the Albert Gallatin School District. Three 16-year-old students were treated and released at Uniontown Hospital after exposure to the noxious fumes.

Police aren’t identifying the suspect because he’s been charged as a juvenile with criminal mischief and disorderly conduct.

The bus had to be taken out of service and cleaned.