More than 30 students went to a local hospital after someone sprayed an unknown substance in their school bus.
It happened 2 p.m. Thursday on Route 15. The students were from Middletown High School students.
Officials said emergency personnel evaluated those on the bus and decided the students and driver should go to the hospital.
Six of the students had complained they were feeling sick, and at the hospital, four students needed evaluation, Frederick County Public Schools spokeswoman Dian Nelson told the Frederick News-Post.
State police are investigating the incident.
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