If the 17 train wagons that derailed in Acornhoek, Mpumalanga, on Sunday evening had not been travelling through a gorge they could have careened into businesses and a hospital next to the railway line.
The wagons derailed between Tintswalo Hospital and several businesses, including a busy car wash.
A motorist at the car wash, less than 100m from the accident, said people ran away as soon as the impact was heard and a huge cloud of dust engulfed them.
"There was a loud bang that made the earth shake in a way that made us believe it was an earthquake or the end of the world.
"Some of us ran away without knowing what we were running from," said Johannes Makhubela.
He said the huge cloud of dust thrown up by the derailment made it impossible for anyone to see that a train had derailed.
Makhubela said many people ran to the scene to loot whatever the wagons were carrying, but were disappointed to discover that the train was transporting "black stuff similar to coal".
The wagons were carrying magnetite, an iron ore.
A woman who sells fruit and vegetables in front of the hospital said: "I prayed that the wagons would not jump out of the gorge and hit the hospital."