Dowdell Middle School in Tampa was briefly evacuated Monday morning.
The school was cleared out after six students and staff became ill from an odor in the main office, Hillsborough County Fire Rescue said.
Crews metered the building to determine whether there was a leak that could have caused the illnesses, officials said. No leak was found, and students and staff were readmitted to their classrooms after about 30 minutes.
About nine students or staff were treated - either from the odor or from the heat after being outside during the evacuation, officials said. None were taken to a hospital, and no other injuries or illnesses were reported.
Dowdell Middle School is located at 1208 Wishing Well Way.