STOCKTON (CBS13) – School officials say a Stockton elementary school class had to evacuate after several students started feeling lightheaded.

The incident happened Thursday morning at Taft Elementary School, according to the Stockton Unified School District.

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A class of 12 students and their teacher reportedly started complaining of lightheadedness, prompting the school to call for first responders. That classroom, along with other nearby classrooms, were evacuated.

First responders evaluated the evacuated students and their teacher and found them all to be stable. One student, however, was taken to the hospital as an extra precaution. The other 11 students were picked up by their parents and told follow up with a doctor.

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Stockton Fire and the Stockton Municipal Utility District inspected the school’s HVAC system and didn’t find any hazardous material, the district says.

Exactly what prompted the incident is still under investigation.

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The rest of the school was allowed to return to class for the rest of the day.