Four people have been taken to hospital after episodes of fitting and fainting were reported at one school.
An ambulance crew was dispatched to Wyvern Academy in Branksome, Darlington, on Tuesday afternoon to reports of a patient having a fit.
The crew, from North East Ambulance Service, arrived around 1pm when it was made aware other patients were also suffering from "fits or faints" in other areas of the school.
In total, the ambulance service transported three patients to hospital and a fourth was making their own way.
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A fifth patient, who crews attended to at the scene, did not require any treatment, the ambulance service has said.
It has not been confirmed what caused the episodes.
It is also unclear if any patients were pupils.
An ambulance spokesperson said: "We received a call from a member of staff at Wyvern Academy just after 1pm on Tuesday for a patient who was fitting.
"While the crew attended to treat the patient, we received reports of other episodes of fits or faints in other parts of the school.
"We took three patients to hospital, another was making their own way and a fifth did not require any treatment."
Wyvern Academy, which had 482 pupils aged 11 to 16 on its roll at its last Ofsted inspection in 2019, declined to comment.
The Mirror has contacted Consilium Academies' Multi-Academy Trust, which operates the school.
A spokesperson for Durham Police confirmed they did not attend the incident.
