The Broken Arrow school district blames a pepper spray pellet for the evacuation of Leisure Park Elementary School Monday morning.
The district said a student brought the pellet to school.
A district spokeswoman said several students and staff members complained of breathing problems and irritation in their eyes, so the district evacuated the school at about 11:15 a.m.
It sent all students and staff members over to Aspen Creek Elementary so they could have lunch and access to restrooms.
The district said medical personnel evaluated the people who complained of breathing problems while the Broken Arrow Fire Department began checking the school.
According to safety experts it takes at least an hour for the fumes to dissipate so the students will spend the rest of the day at Aspen Creek.