A temporary bridge that was part of a construction project collapsed onto one of South Africa's busiest highways on Wednesday, killing two people and injuring 21 others, South Africa media reported.

Those killed in the accident at the M1 highway on the edge of Johannesburg's Sandton district included a taxi driver, news channel eNCA reported, citing emergency responders.

The news channel quoted a construction company as saying the temporary bridge was a support structure being used in the building of a pedestrian and cycling bridge over the highway. The construction project is designed to connect Sandton, an affluent area, with the poor neighborhood of Alexandra.

Photographs of the scene showed at least two vehicles partly crushed beneath scaffolding from the support structure. The accident happened in the afternoon, forcing road closures and traffic jams at rush hour.