A primary school teacher at a school in Mayfair, Johannesburg, risked his life to protect pupils from a knife-wielding trespasser on Thursday afternoon.

According to Huguenot Primary school Principal NZ Tilly, the man appeared to be hallucinating and had jumped over the school's fence 'looking for his wife'.

He said a teachers, H Zardad, was on the top floor when he heard children screaming near the front of the school where the parking lot was.

When he rushed to see what was happening, he saw a man wielding a knife insisting that he had seen his wife on the premises and was looking for her.

Zardad managed to restrain the man and take him to the staff room, away from the children.

"It was a close call. He put his life at stake. That was an act of bravery," Tilly said.

By the time Zardad and the man reached the staff room, private security personnel and police had already arrived. He was subsequently arrested and taken to the Brixton police station.

Police were unable to provide information on the incident.

Tilly declined speculate on whether the man appeared to be under the influence of any substances, but described his mannerisms as "very strange".

The incident occurred at around 12.25, shortly after the second interval bell had rung, Tilly said. Fortunately, the man had not come into contact with any of the children as most had already returned to class.

Those that had seen the man however, would receive counselling, Tilly said.

News24