Two suspected robbers were killed in a shootout with police during a break-in at a Johannesburg high school as students prepared to sit exams on Thursday, officials said.

A gang of robbers stormed the school, intimidated office staff and demanded access to the safe before making off with 8,000 rands ($572).

Police and private security officers responded to the unfolding emergency in minutes.

“When they (police) arrived the suspects were on their way out, the shooting started and that’s when the police returned fire,” police spokesman Kay Makhubela told reporters outside the school.

“Two suspects were shot and killed,” he said adding that another was injured, two others arrested while an unknown number fled in two vehicles.

No staff or students were wounded in the attack.

The head of Edenvale High School Larry Harmer said he watched on the security camera as the robbers forced their way into the school when a parent came to collect his child. It was too late to lock them out.

“They jumped through the window with their AK-47s and pistols and then traumatised thefront staff and office staff, and demanded the safe,” said Harmer.

Gauteng Provincial Education Minister Panyaza Lesufi said students were sent home after the attack and all classes and exams were suspended until Monday.

“(Schools) are sitting ducks of criminals,” said Lesufi.

Violent crime is notoriously common in South Africa, with armed robbery, rape, carjacking and muggings among the leading threats. (AFP)