At least three students are dead and “scores” are trapped in the rubble after a walkway collapsed at a school outside Johannesburg, a South African official said Friday.

Panyaza Lesufi, the head of education for Gauteng province, posted the toll on Twitter shortly after the collapse at the Hoerskool Driehoek high school in Vanderbijlpark.

It was not immediately clear what caused the collapse.

Emergency services provider Netcare911 said at least four people may have died and at least five people were critically injured.

The national Department of Education extended condolences to the families of the students killed.

A statement by AfriForum, a civil society organization that represents the rights of Afrikaners, sent out a notice urging people to avoid the area so as not to interfere with the work of emergency responders.

(AP)