The train was travelling on BHP's Newman to Port Hedland line in the Pilbara region, a remote area.
A runaway BHP Billiton train loaded with thousands of tonnes of iron ore travelled more than 90km across Western Australia without a driver before being deliberately derailed.
The Australian Transport Safety Bureau said the train, operated by Australian mining company BNP, was traveling from Newman to the coastal city of Port Headland when the driver stopped the train to inspect a vehicle.
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Iron ore alone is responsible for nearly 40 percent of BHP's earnings before interest, tax, depreciation and amortization (EBITA).
The Australian Transport Safety Bureau is looking into the incident, but says its investigation won't be complete until the second quarter of next year.
The company said the driver was inspecting an issue with the train when the locomotive ran away. "We are working with the appropriate authorities to investigate the situation", a BHP spokesperson said, as quoted by the Financial Times.
But the train took off from the siding before the driver could get back on board.