At least three students have died following a walkway collapsed at a school in South Africa.

It happened at Hoërskool Driehoek high school in Vanderbijlpark, just south of Johannesburg.

Two boys and one girl were killed in the incident, officials confirmed.

23 other students are said to have been injured, with emergency service provider Netcare911 saying five were in a critical condition.

Gauteng Bridge collapse update: Latest report from scene, 5 ppl in a critical condition, 3 ppl have been airlifted, multiple other injuries ranging from minor to moderate, update to follow. pic.twitter.com/uQiWIC0TaZ

— Netcare911 (@Netcare911_sa) February 1, 2019

Panyaza Lesufi, the head of education in the region, earlier said "scores" had been trapped in the rubble.

Details of what caused the collapse were not immediately clear, with a police investigation now underway to figure out what happened.