Parents have been offered reassurance after four students were hospitalised following reports of "seizures and faints".
Ambulance crews attended Wyvern Academy in Darlington on Tuesday and took four students to hospital.
The North East Ambulance Service said it was called to reports of a pupil having a seizure, and the school in the Eggleston View area of the city has since confirmed the ambulance was initially called to student who was having an epileptic seizure.
