A pepper spray incident forced the evacuation of Mesa High School on Thursday.
Someone released the pepper spray at the end of the school day in one of the hallways on the first floor of the school.
Mesa HAZMAT crews eventually cleared the school. No one suffered injuries or lingering effects from the pepper spray.
The students were later released to go home.
Just a few weeks ago, several teenagers who attend the school were taken to the hospital after having heart palpitations, allegedly from smoking a synthetic drug.