The incident occurred at Kia Aroha College, Clover Park, about 10.30am.
A spokesperson at Kia Aroha College confirmed the medical incident to The New Zealand Herald around 11am as teachers were entering an emergency meeting to discuss the situation.
Shortly after this, the death of a pupil was confirmed on the Kia Aroha College's Facebook page by principal Haley Milne.
"He aituā, he aituā! Our beautiful tama [name of pupil] has passed away at our school today. We are currently sending all of our young people home while we wait for the details of his tangi," Milne said.
"Once we have details we will post them here. Our school will be closed in the meantime."
The Herald has sought comment from emergency services.