At least 644 people were injured, two critically, when two trains collided outside Johannesburg, South African media reported on Friday. The incident took place after nightfall on Thursday near the Soweto township. About 150 people have been taken to hospital. According to news agency SAPA, a moving train seems to have collided head-on with stationary a train at a station. One witness described the scenes at the wreck as horrible, as dpa reported.