Hundreds of people were injured when a commuter express smashed into a stationary train in Johannesburg's Soweto township.

Two people were in a critical condition after the crash, which happened during rush hour yesterday as people made their way home from work, rail operator Metrorail said. No-one was killed.

‘We have around 857 people that were injured,’ Metrorail acting regional manager Douglas Chauke told AFP.

‘Only two were critically injured, the rest were minor injuries.’

The coaches remained on the tracks and most of the injured had already been discharged from hospital, he said.

‘The train didn't derail. There were actually minor damages to the infrastructure and also the train itself was damaged but not seriously.’

The cause of the accident is being investigated by the Railway Safety Regulator which said the passenger train was travelling toward Orlando when it hit a stationary Soweto Business Express train.

‘The injured were assisted by emergency services at scene and taken to nearby hospitals,’ the regulator said in a statement.

The number of people onboard the train was unknown but Metorail's carrying capacity estimates the number at between 2,000 and 2,500 people.