Two trains have collided south of Johannesburg, killing the conductor of one of the trains and injuring about 80 people.

A spokesman for ER24 emergency services, Russel Meiring, said the driver of one of the trains was declared dead at the scene on Tuesday.

Meiring said in a statement that a woman passenger was trapped between the train and a wall. Rescue workers freed her before airlifting her to a hospital.

The statement said the cause of the crash is not yet known, and investigations are underway.