Students at the county-run high school at Camarillo Airport were evacuated Thursday morning after the accidental release of pepper spray.
It happened around 8:20 AM at the facility on Airport Way.
Four people were assessed at the scene by medical personnel.
One of them was taken to the hospital with minor injuries.
The other three were treated and released at the scene.
The school facility was being checked out so that students could return to class asap.