Eight boys from King Edward VIII School (KES) in Johannesburg were struck by lightning, paramedics said.
The eight had been taken to Milpark hospital where they were being assessed and treated, Netcare 911 spokeswoman Santi Steinmann said.
Details on their condition were not immediately available.
A security guard at the main gate of the school was controlling the entrance as parents came to fetch their children on Tuesday night.
A school official, who did not want to be named said: “No comment at this stage from the school. Can all queries please be directed to the provincial education department.”
Two Netcare 911 cars were seen leaving the school premises from the direction of the cricket field.
School boys, dressed in cricket attire, were asked not to speak to anyone.